WO2019155881A1 - Carbon material, electrode for electricity storage devices, electricity storage device, and nonaqueous electrolyte secondary battery - Google Patents

Carbon material, electrode for electricity storage devices, electricity storage device, and nonaqueous electrolyte secondary battery Download PDF

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Publication number
WO2019155881A1
WO2019155881A1 PCT/JP2019/001980 JP2019001980W WO2019155881A1 WO 2019155881 A1 WO2019155881 A1 WO 2019155881A1 JP 2019001980 W JP2019001980 W JP 2019001980W WO 2019155881 A1 WO2019155881 A1 WO 2019155881A1
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Prior art keywords
carbon material
less
electrode
electricity storage
positive electrode
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PCT/JP2019/001980
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French (fr)
Japanese (ja)
Inventor
裕樹 澤田
増田　浩樹
直樹 笹川
内田　かずほ
藤原　昭彦
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積水化学工業株式会社
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Application filed by 積水化学工業株式会社 filed Critical 積水化学工業株式会社
Priority to JP2019515389A priority Critical patent/JP7164517B2/en
Priority to KR1020207016766A priority patent/KR20200119231A/en
Priority to EP19751288.2A priority patent/EP3751647A4/en
Priority to US16/966,441 priority patent/US20200365895A1/en
Priority to CN201980012435.9A priority patent/CN111699580A/en
Publication of WO2019155881A1 publication Critical patent/WO2019155881A1/en

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Definitions

  • the present invention relates to a carbon material having a graphene laminated structure, and an electrode for an electricity storage device, an electricity storage device, and a nonaqueous electrolyte secondary battery using the carbon material.
  • Patent Document 1 discloses a nonaqueous electrolyte secondary battery including a positive electrode in which an active material layer is provided on a current collector.
  • the active material layer of the positive electrode in the nonaqueous electrolyte secondary battery of Patent Document 1 includes a plurality of active material particles and graphene as a carbon material.
  • Patent Document 1 describes that the oxygen concentration of this graphene is 2 atomic% or more and 20 atomic% or less.
  • Patent Document 2 discloses a lithium ion secondary battery including an electrode including a carbon material and an active material.
  • Patent Document 2 discloses a carbon material having a structure in which graphite is partially exfoliated as an example of the carbon material.
  • An object of the present invention is to provide a carbon material, an electrode for an electricity storage device using the carbon material, an electricity storage device, and a nonaqueous electrolyte secondary battery that can improve battery characteristics represented by the cycle characteristics of the electricity storage device. is there.
  • the carbon material according to the present invention when measuring an X-ray diffraction spectrum of a carbon material having a graphene laminated structure in a weight ratio of 1: 1 between the carbon material and Si, 2 ⁇ is The ratio a / b between the highest peak height a in the range of 24 ° or more and less than 28 ° and the highest peak height b in the range of 2 ⁇ of 28 ° or more and less than 30 ° is 0.2
  • the volume ratio of LiPF 6 having a concentration of 1 mol / L and ethylene carbonate to dimethyl carbonate is 1:10, which is 10.0 or less and the electrode containing the carbon material is a working electrode, lithium metal is a reference electrode and a counter electrode.
  • the absolute value of the current value in the potential of 4.25V as measured by cyclic voltammetry is 0. 01A / g or more, it is less than or equal to 0.02A / g.
  • the ratio a / b between the highest peak height a in the range of 24 ° or more and less than 28 ° and the highest peak height b in the range of 2 ⁇ of 28 ° or more and less than 30 ° is 0
  • the ratio of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less.
  • the carbon material is exfoliated graphite.
  • the carbon material is used for an electrode for an electricity storage device.
  • the electrode for an electricity storage device according to the present invention includes a carbon material configured according to the present invention.
  • An electricity storage device includes an electrode for an electricity storage device configured according to the present invention.
  • a non-aqueous electrolyte secondary battery according to the present invention includes an electrode for an electricity storage device configured according to the present invention and a non-aqueous electrolyte.
  • the non-aqueous electrolyte is an electrolytic solution in which a solute is dissolved in a non-aqueous solvent, and 0.0 V or more with respect to Li / Li + .
  • a compound that reacts at 0 V or less, and the content of the compound is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte.
  • the non-aqueous electrolyte is 2.0 V or higher with respect to an electrolytic solution obtained by dissolving a solute in a non-aqueous solvent, and Li / Li + .
  • the compound reacts at 0.0 V or less, and the content of the compound is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the non-aqueous electrolyte.
  • the present invention it is possible to provide a carbon material, an electrode for an electricity storage device using the carbon material, an electricity storage device, and a nonaqueous electrolyte secondary battery that can improve battery characteristics represented by the cycle characteristics of the electricity storage device. it can.
  • the power storage device of the present invention is not particularly limited, but a non-aqueous electrolyte primary battery, an aqueous electrolyte primary battery, a non-aqueous electrolyte secondary battery, an aqueous electrolyte secondary battery, an all-solid electrolyte primary battery, an all-solid electrolyte secondary battery, Examples thereof include a capacitor, an electric double layer capacitor, and a lithium ion capacitor.
  • the carbon material of the present invention is an electrode material included in the electrode for an electricity storage device as described above.
  • the electrode for an electricity storage device of the present invention is an electrode used for the above electricity storage device.
  • the carbon material of the present invention is a carbon material contained in an electrode for an electricity storage device.
  • the carbon material includes a carbon material having a graphene stacked structure.
  • the absolute value of the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry using the electrode containing the carbon material as a working electrode is 0.00. It is 001 A / g or more and 0.02 A / g or less.
  • the inventors of the present application have found that the reactivity between the carbon material and the electrolytic solution correlates with the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry. That is, by setting the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry within the above range, the reactivity between the carbon material and the electrolytic solution can be reduced. As a result, it has been found that the battery characteristics of an electricity storage device represented by cycle characteristics can be improved.
  • the ratio of the number of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less.
  • the C / O ratio is not less than the above lower limit, the reactivity between the carbon material and the electrolytic solution can be reduced. This is considered to be because the amount of oxygen atoms contained in the electrode is reduced, thereby further suppressing the reaction with the electrolytic solution.
  • the adverse effect on the counter electrode can be further reduced by reducing the reaction product.
  • battery characteristics represented by cycle characteristics can be further improved.
  • the C / O ratio is less than or equal to the above upper limit, an electron conduction path can be easily formed, and rate characteristics can be improved.
  • examples of the carbon material having a graphene laminated structure include graphite and exfoliated graphite.
  • Graphite is a laminate of a plurality of graphene sheets.
  • the number of graphite graphene sheets laminated is usually about 100,000 to 1,000,000.
  • As the graphite for example, natural graphite, artificial graphite or expanded graphite can be used. Expanded graphite is preferable because the ratio of the distance between the graphene layers is larger than that of normal graphite, and the liquid retaining property of the electrolytic solution may be further increased.
  • Exfoliated graphite refers to a graphene sheet laminate that is obtained by exfoliating the original graphite and is thinner than the original graphite.
  • the number of graphene sheets laminated in exfoliated graphite should be less than the original graphite.
  • the exfoliated graphite may be oxidized exfoliated graphite.
  • the number of laminated graphene sheets is not particularly limited, but is preferably 2 layers or more, more preferably 5 layers or more, preferably 1000 layers or less, more preferably 500 layers or less.
  • the conductivity of exfoliated graphite can be further enhanced.
  • the specific surface area of exfoliated graphite can be further increased.
  • the exfoliated graphite is preferably partially exfoliated graphite having a structure in which the graphite is partially exfoliated.
  • the graphene layer in the graphene laminate, is open from the edge to some extent, that is, a part of the graphite is exfoliated at the edge.
  • the graphite layer In the central part, the graphite layer is laminated similarly to the original graphite or primary exfoliated graphite. Therefore, the part where the graphite is partially peeled off at the edge is continuous with the central part.
  • the partially exfoliated exfoliated graphite may include one obtained by exfoliating the edge graphite.
  • the graphite layer is laminated at the center side in the same manner as the original graphite or primary exfoliated graphite. Therefore, the degree of graphitization is higher than that of conventional graphene oxide and carbon black, and the conductivity is excellent. Moreover, since it has a structure in which graphite is partially peeled off, the specific surface area is large. As a result, the area of the portion in contact with the active material can be increased. Therefore, when the electrode material for an electricity storage device containing partially exfoliated graphite is used for an electrode of an electricity storage device such as a secondary battery, the resistance of the electricity storage device can be further reduced, Heat generation during charging / discharging can be further suppressed.
  • the partially exfoliated graphite includes, for example, graphite or primary exfoliated graphite and a resin, and a composition in which the resin is fixed to the graphite or primary exfoliated graphite by grafting or adsorption is prepared.
  • a composition in which the resin is fixed to the graphite or primary exfoliated graphite by grafting or adsorption is prepared.
  • the resin When the resin is thermally decomposed, it may be thermally decomposed while leaving a part of the resin, or the resin may be completely thermally decomposed.
  • the partially exfoliated exfoliated graphite can be produced by, for example, the same method as the exfoliated graphite / resin composite material described in International Publication No. 2014/034156. Further, as graphite, it is preferable to use expanded graphite because it can be more easily peeled off.
  • primary exfoliated graphite widely includes exfoliated graphite obtained by exfoliating graphite by various methods.
  • the primary exfoliated graphite may be partially exfoliated graphite. Since primary exfoliated graphite is obtained by exfoliating graphite, the specific surface area may be larger than that of graphite.
  • the heating temperature in the thermal decomposition of the resin is not particularly limited depending on the type of the resin, but may be, for example, 250 ° C. to 1000 ° C.
  • the heating time can be, for example, 20 minutes to 5 hours.
  • the said heating may be performed in air
  • inert gas atmosphere such as nitrogen gas.
  • the resin is not particularly limited, but is preferably a polymer of a radical polymerizable monomer. In this case, it may be a homopolymer of one kind of radically polymerizable monomer or a copolymer of plural kinds of radically polymerizable monomers.
  • the radical polymerizable monomer is not particularly limited as long as it is a monomer having a radical polymerizable functional group.
  • radical polymerizable monomer examples include styrene, methyl ⁇ -ethyl acrylate, methyl ⁇ -benzyl acrylate, methyl ⁇ - [2,2-bis (carbomethoxy) ethyl] acrylate, dibutyl itaconate, dimethyl itaconate.
  • Examples of the resin used include polyethylene glycol, polypropylene glycol, polyglycidyl methacrylate, polyvinyl acetate, polyvinyl butyral (butyral resin), poly (meth) acrylate, and polystyrene.
  • polyethylene glycol, polypropylene glycol, and polyvinyl acetate can be preferably used.
  • polyethylene glycol, polypropylene glycol, or polyvinyl acetate is used, the specific surface area of the partially exfoliated exfoliated graphite can be further increased.
  • the resin type can be appropriately selected in view of the affinity with the solvent used.
  • the content of the resin before pyrolysis fixed to graphite or primary exfoliated graphite is preferably 0.1 parts by weight or more, more preferably 0, per 100 parts by weight of graphite or primary exfoliated graphite excluding the resin component. 0.5 parts by weight or more, preferably 3000 parts by weight or less, more preferably 1000 parts by weight or less.
  • the content of the resin before pyrolysis is within the above range, it is easier to control the content of the residual resin after pyrolysis. Further, when the content of the resin before thermal decomposition is not more than the above upper limit value, it is more advantageous in terms of cost.
  • the content of the residual resin after pyrolysis is preferably 0% by weight or more and 30% by weight or less with respect to 100% by weight of partially exfoliated exfoliated graphite including the resin component, and is 0.5% by weight or more, 25
  • the amount is more preferably at most%, more preferably at least 1.0% by weight and at most 20% by weight.
  • the amount of the resin is not less than the above lower limit, the amount of the binder resin added at the time of producing the electrode can be further reduced.
  • the said resin amount is below the said upper limit, the reactivity of the carbon material mentioned above and electrolyte solution can be made still smaller.
  • the resin content before thermal decomposition and the residual resin amount remaining in the partially exfoliated graphite can be calculated, for example, by measuring the weight change with the heating temperature by thermogravimetric analysis (hereinafter, TG). Can do.
  • TG thermogravimetric analysis
  • the amount of the resin may be reduced or the resin may be removed after preparing the composite with the positive electrode active material.
  • a method of performing a heat treatment at a temperature equal to or higher than the decomposition temperature of the resin and lower than the decomposition temperature of the positive electrode active material is preferable.
  • This heat treatment may be performed in the air, in an inert gas atmosphere, in a low oxygen atmosphere, or in a vacuum.
  • the peak ratio a / b is 0.2 or more, preferably 0.22 or more, more preferably Is 0.25 or more.
  • the peak ratio a / b is 10.0 or less, preferably 8.0 or less, and more preferably 5.0 or less.
  • the a is the highest peak height in a range where 2 ⁇ is 24 ° or more and less than 28 °.
  • the b is the highest peak height in a range where 2 ⁇ is 28 ° or more and less than 30 °.
  • the X-ray diffraction spectrum can be measured by a wide angle X-ray diffraction method.
  • X-rays CuK ⁇ rays (wavelength 1.541 ⁇ ) can be used.
  • SmartLab manufactured by Rigaku Corporation
  • Rigaku Corporation can be used as the X-ray diffraction apparatus.
  • the formation of the graphite structure in the carbon material itself is immature, and in addition to low electronic conductivity, it has defects, so that the resistance value of the positive electrode and the negative electrode increases, and battery characteristics are increased. May decrease.
  • the carbon material itself becomes rigid and difficult to disperse in the positive electrode or negative electrode of the electricity storage device, and it may be difficult to form a good electron conduction path.
  • a / b is fixed to the heating conditions when pyrolyzing the partially exfoliated graphite, or to graphite or primary exfoliated graphite. It can adjust with the quantity of resin before thermal decomposition. For example, a / b can be reduced by increasing the heating temperature or increasing the heating time. Moreover, a / b can be reduced by reducing the amount of the resin before pyrolysis fixed to graphite or primary exfoliated graphite.
  • the absolute value of is 0.001 A / g or more and 0.02 A / g or less.
  • the absolute value of the current is preferably 0.003 A / g or more, more preferably 0.005 A / g or more, preferably 0.019 A / g or less, more preferably 0.018 A / g or less.
  • an electrode containing the carbon material of the present invention is used as a working electrode.
  • An electrode made of lithium metal is used as a reference electrode and a counter electrode.
  • an electrolytic solution containing 1 mol / L concentration of LiPF 6 and a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1: 2 is used.
  • the electron conduction path can be more easily formed, and the rate The characteristics can be further enhanced.
  • the absolute value of the said current is below the said upper limit, the reactivity of a carbon material and electrolyte solution can be made still smaller, and the battery characteristic represented by cycling characteristics can be improved further.
  • the absolute value of the current is adjusted by adjusting the amount of the resin described above, changing the heating conditions described above, or performing the heating during the pyrolysis described above in an inert gas atmosphere. Can do. Specifically, for example, when the carbon material is partially exfoliated graphite, reducing the amount of resin before pyrolysis fixed to graphite or primary exfoliated graphite can reduce the absolute value of the current. it can. Further, in the heating during the above-described thermal decomposition, the absolute value of the current can be reduced by increasing the concentration of the inert gas and decreasing the oxygen concentration.
  • the ratio of the number of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less.
  • the C / O ratio is more preferably 22 or more, further preferably 25 or more, more preferably 180 or less, More preferably, it is 160 or less.
  • the C / O ratio can be measured by, for example, X-ray photoelectron spectroscopy (XPS). Specifically, the photoelectron spectrum is measured under the conditions of X-ray source: AlK ⁇ , photoelectron extraction angle: 45 degrees, and X-ray beam diameter of 200 ⁇ m (50 W 15 kV). Then, the peak area of the C1s spectrum appearing at Binding Energy: 280 eV to 292 eV is divided by the peak area of the O1s spectrum appearing at Binding Energy: 525 eV to 540 eV. Thereby, the ratio (C / O ratio) of the number of carbon atoms to the number of oxygen atoms contained in the carbon material can be calculated.
  • XPS X-ray photoelectron spectroscopy
  • the C / O ratio is adjusted by adjusting the amount of the resin, changing the heating condition, or performing the heating in the pyrolysis under an inert gas atmosphere. Can do. Specifically, for example, when the carbon material is partially exfoliated graphite, the C / O ratio is increased by reducing the amount of resin before pyrolysis fixed to graphite or primary exfoliated graphite. Can do. Further, in the heating during the above-described thermal decomposition, the C / O ratio can be increased by increasing the concentration of the inert gas and decreasing the oxygen concentration.
  • the BET specific surface area of the carbon material of the present invention is not particularly limited, but is preferably 10 m 2 / g or more, more preferably 15 m 2 / g or more, preferably 200 m 2 / g or less, more preferably 160 m 2 / g or less. is there.
  • the BET specific surface area of a carbon material is more than the said minimum, the liquid retention property of electrolyte solution can be improved further and battery characteristics, such as the capacity
  • the BET specific surface area of a carbon material is below the said upper limit, the coating property at the time of forming the electrode by coating the slurry containing the said carbon material on a collector can be improved further. In addition, the conductivity can be further increased. Furthermore, since the reaction field between the carbon material and the electrolytic solution is reduced, the deterioration of the electrolytic solution can be further suppressed.
  • the BET specific surface area of the carbon material of the present invention can be measured from a nitrogen adsorption isotherm according to the BET method.
  • a measuring device for example, product number “ASAP-2000” manufactured by Shimadzu Corporation can be used.
  • the carbon material of the present invention can be used for an electrode for an electricity storage device, that is, a positive electrode and / or a negative electrode of the electricity storage device.
  • an electrode for an electricity storage device that is, a positive electrode and / or a negative electrode of the electricity storage device.
  • the cycle characteristics can be further improved, so it is preferably used as a positive electrode conductive aid. be able to.
  • the conductivity of the positive electrode can be further increased by using the carbon material of the present invention, so that the content of the conductive auxiliary agent in the positive electrode can be reduced. Therefore, the content of the positive electrode active material can be further increased, and the energy density of the electricity storage device can be further increased.
  • the positive electrode may have a general positive electrode configuration, composition, and manufacturing method, or a composite of the positive electrode active material and the carbon material of the present invention.
  • the electrode for the electricity storage device is a negative electrode
  • the negative electrode active material for example, natural graphite, artificial graphite, hard carbon, metal oxide, lithium titanate, or silicon-based active material can be used.
  • the content of the carbon material in 100% by weight of the electrode for an electricity storage device is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, further preferably 0.4% by weight or more, preferably 10% by weight. % Or less, more preferably 8% by weight or less, and still more preferably 5% by weight or less.
  • the content of the carbon material is within the above range, the content of the active material can be further increased, and the energy density of the electricity storage device can be further increased.
  • the carbon material of the present invention when the carbon material of the present invention is the first carbon material (unless otherwise specified, it is simply referred to as a carbon material), it is different from the first carbon material.
  • a second carbon material may be further included.
  • the second carbon material is not particularly limited, and graphene, artificial graphite, granular graphite compound, fibrous graphite compound, carbon black or activated carbon is exemplified.
  • a positive electrode for a secondary battery as an example of an electrode for an electricity storage device of the present invention will be described.
  • the same binder etc. can be used also when the electrode for electrical storage devices is a negative electrode for secondary batteries.
  • the positive electrode active material used for the electrode for the electricity storage device of the present invention may be nobler than the battery reaction potential of the negative electrode active material.
  • the battery reaction should just involve group 1 or group 2 ions.
  • examples of such ions include H ions, Li ions, Na ions, K ions, Mg ions, Ca ions, and Al ions.
  • examples of the positive electrode active material include lithium metal oxide, lithium sulfide, and sulfur.
  • lithium metal oxide examples include those having a spinel structure, a layered rock salt structure, an olivine structure, or a mixture thereof.
  • lithium metal oxide having a spinel structure examples include lithium manganate.
  • lithium metal oxide having a layered rock salt structure examples include lithium cobaltate, lithium nickelate, and ternary system.
  • lithium metal oxide having an olivine structure examples include lithium iron phosphate, lithium manganese iron phosphate, and lithium manganese phosphate.
  • the positive electrode active material may contain a so-called doping element.
  • the said positive electrode active material may be used independently and may use 2 or more types together.
  • the positive electrode may be formed only of the positive electrode active material and the carbon material, but a binder may be included from the viewpoint of forming the positive electrode more easily.
  • the binder is not particularly limited.
  • at least one resin selected from the group consisting of polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber, polyimide, and derivatives thereof is used.
  • PVdF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • styrene-butadiene rubber polyimide, and derivatives thereof is used.
  • the above binder is preferably dissolved or dispersed in a non-aqueous solvent or water from the viewpoint of more easily producing a positive electrode for a secondary battery.
  • the non-aqueous solvent is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, ethyl acetate, and tetrahydrofuran. You may add a dispersing agent and a thickener to these.
  • NMP N-methyl-2-pyrrolidone
  • dimethylformamide dimethylacetamide
  • methyl ethyl ketone methyl acetate
  • ethyl acetate tetrahydrofuran
  • the amount of the binder contained in the positive electrode for a secondary battery is preferably 0.3 parts by weight or more and 30 parts by weight or less, more preferably 0.5 parts by weight or more, with respect to 100 parts by weight of the positive electrode active material. 15 parts by weight or less.
  • the amount of the binder is within the above range, the adhesion between the positive electrode active material and the carbon material can be maintained, and the adhesion with the current collector can be further enhanced.
  • Examples of the method for producing the positive electrode for a secondary battery include a method of producing a mixture of a positive electrode active material, a carbon material, and a binder on a current collector.
  • a slurry is prepared by adding and mixing a binder solution or a dispersion liquid to a positive electrode active material and a carbon material.
  • the produced slurry is applied on a current collector, and finally the solvent is removed to produce a positive electrode for a secondary battery.
  • an existing method can be used.
  • the method of mixing using a mixer etc. is mentioned.
  • a planetary mixer, a disper, a thin film swirl-type mixer, a jet mixer, or a self-rotation type mixer etc. are mentioned.
  • the solid content concentration of the slurry is preferably 30% by weight or more and 95% by weight or less from the viewpoint of facilitating coating. From the viewpoint of further improving the storage stability, the solid content concentration of the slurry is more preferably 35% by weight or more and 90% by weight or less. Further, from the viewpoint of further reducing the production cost, the solid content concentration of the slurry is more preferably 40% by weight or more and 85% by weight or less.
  • the solid content concentration can be controlled by a diluent solvent.
  • a diluent solvent As the diluting solvent, it is preferable to use the same type of solvent as the binder solution or dispersion. Further, other solvents may be used as long as the solvents are compatible.
  • the current collector used for the positive electrode for the secondary battery is preferably aluminum or an alloy containing aluminum.
  • Aluminum is not particularly limited because it is stable in the positive electrode reaction atmosphere, but is preferably high-purity aluminum represented by JIS standards 1030, 1050, 1085, 1N90, 1N99, and the like.
  • the thickness of the current collector is not particularly limited, but is preferably 10 ⁇ m or more and 100 ⁇ m or less. When the thickness of the current collector is less than 10 ⁇ m, handling may be difficult from the viewpoint of production. On the other hand, when the thickness of the current collector is thicker than 100 ⁇ m, it may be disadvantageous from an economic viewpoint.
  • the current collector may be one in which the surface of a metal other than aluminum (copper, SUS, nickel, titanium, and alloys thereof) is coated with aluminum.
  • the method of applying the slurry to the current collector is not particularly limited.
  • the method of removing the solvent after applying the slurry with a doctor blade, die coater or comma coater, or removing the solvent after applying with a spray is mentioned.
  • the method for removing the solvent is more simple, drying using a blowing oven or a vacuum oven is preferable.
  • the atmosphere for removing the solvent include an air atmosphere, an inert gas atmosphere, and a vacuum state.
  • the temperature for removing the solvent is not particularly limited, but is preferably 60 ° C. or higher and 250 ° C. or lower. If the temperature at which the solvent is removed is less than 60 ° C., it may take time to remove the solvent. On the other hand, if the temperature for removing the solvent is higher than 250 ° C., the binder may deteriorate.
  • the secondary battery positive electrode may be compressed to a desired thickness and density.
  • compression is not specifically limited, For example, it can carry out using a roll press, a hydraulic press, etc.
  • the thickness of the positive electrode for secondary battery after compression is not particularly limited, but is preferably 10 ⁇ m or more and 1000 ⁇ m or less. If the thickness is less than 10 ⁇ m, it may be difficult to obtain a desired capacity. On the other hand, when the thickness is thicker than 1000 ⁇ m, it may be difficult to obtain a desired output density.
  • the positive electrode for secondary battery preferably has an electric capacity per 1 cm 2 of positive electrode of 0.5 mAh or more and 10.0 mAh or less.
  • the electric capacity is less than 0.5 mAh, the size of the battery having a desired capacity may increase.
  • the electric capacity is greater than 10.0 mAh, it may be difficult to obtain a desired output density.
  • the calculation of the electric capacity per 1 cm 2 of the positive electrode may be performed by preparing a half battery using a lithium metal as a counter electrode after preparing the positive electrode for the secondary battery and measuring the charge / discharge characteristics.
  • the electric capacity per 1 cm 2 of the positive electrode of the secondary battery positive electrode is not particularly limited, but can be controlled by the weight of the positive electrode formed per current collector unit area. For example, it can control by the coating thickness at the time of the above-mentioned slurry coating.
  • the positive electrode may be a composite of a positive electrode active material and the carbon material.
  • the positive electrode active material-carbon material composite is produced, for example, by the following procedure.
  • carbon material dispersion 1 a carbon material dispersion in which the above carbon material is dispersed in a solvent
  • carbon material dispersion 1 a carbon material dispersion in which the above carbon material is dispersed in a solvent
  • positive electrode active material dispersion liquid 2 a positive electrode active material dispersion liquid in which a positive electrode active material is dispersed in a solvent
  • the carbon material dispersion 1 and the positive electrode active material dispersion 2 are mixed. Finally, by removing the solvent of the dispersion liquid containing the carbon material and the positive electrode active material, a composite of the positive electrode active material and the carbon material used for the electrode for the electricity storage device (active material-carbon material composite) Is produced.
  • the order of mixing may be changed, and either of the dispersions 1 and 2 may be dry instead of the dispersion, or a method of mixing all in a dry state. But you can. Moreover, you may serve as the method of mixing the mixture of a carbon material, a positive electrode active material, and a solvent with a mixer, ie, preparation of the below-mentioned positive electrode slurry, and preparation of a composite.
  • the solvent in which the positive electrode active material and the carbon material are dispersed may be any of aqueous, non-aqueous, a mixed solvent of aqueous and non-aqueous, or a mixed solvent of different non-aqueous solvents.
  • the solvent for dispersing the carbon material and the solvent for dispersing the positive electrode active material may be the same or different. If they are different, it is preferable that the solvents are compatible with each other.
  • the non-aqueous solvent is not particularly limited.
  • a non-aqueous solvent such as methanol, ethanol, propanol represented by propanol, tetrahydrofuran, or N-methyl-2-pyrrolidone can be used for ease of dispersion.
  • the solvent may contain a dispersant such as a surfactant.
  • the dispersion method is not particularly limited, and examples include dispersion by ultrasonic waves, dispersion by a mixer, dispersion by a jet mill, and dispersion by a stirrer.
  • the solid content concentration of the carbon material dispersion is not particularly limited, but when the weight of the carbon material is 1, the weight of the solvent is preferably 0.5 or more and 1000 or less. From the viewpoint of further improving the handleability, when the weight of the carbon material is 1, the weight of the solvent is more preferably 1 or more and 750 or less. Further, from the viewpoint of further improving dispersibility, when the weight of the carbon material is 1, the weight of the solvent is more preferably 2 or more and 500 or less.
  • the carbon material may not be dispersed to a desired dispersion state.
  • the weight of the solvent is larger than the above upper limit, the production cost may increase.
  • the solid content concentration of the positive electrode active material dispersion is not particularly limited, but when the weight of the positive electrode active material is 1, the weight of the solvent is preferably 0.5 or more and 100 or less. From the viewpoint of further improving the handleability, the weight of the solvent is more preferably 1 or more and 75 or less. Further, from the viewpoint of further improving dispersibility, the weight of the solvent is more preferably 5 or more and 50 or less. In addition, when the weight of the solvent is less than the lower limit, the positive electrode active material may not be dispersed to a desired dispersion state. On the other hand, when the weight of the solvent is larger than the above upper limit, the production cost may increase.
  • the method of mixing the dispersion of the positive electrode active material and the dispersion of the carbon material is not particularly limited, but a method of mixing each other's dispersion at once, or one dispersion into the other dispersion multiple times. A method of adding them separately is mentioned.
  • Examples of the method of adding one dispersion to the other dispersion in a plurality of times include a method of dropping using a dropping device such as a spoid, a method of using a pump, or a method of using a dispenser.
  • the method for removing the solvent from the mixture of the carbon material, the positive electrode active material and the solvent is not particularly limited, and examples thereof include a method of removing the solvent by filtration and then drying it in an oven or the like.
  • the filtration is preferably suction filtration from the viewpoint of further improving productivity.
  • a drying method when drying in a vacuum oven and then drying in a vacuum, it is preferable because the solvent remaining in the pores can be removed.
  • the weight ratio of the positive electrode active material to the carbon material in the active material-carbon material composite is such that the weight of the carbon material is 0.2% by weight or more when the weight of the positive electrode active material is 100% by weight. It is preferable that it is 0.0 weight% or less. From the viewpoint of further improving the rate characteristics, the weight of the carbon material is more preferably 0.3% by weight or more and 8.0% by weight or less. Further, from the viewpoint of further improving the cycle characteristics, the weight of the carbon material is more preferably 0.5% by weight or more and 7.0% by weight or less.
  • An electricity storage device of the present invention includes the electrode for an electricity storage device of the present invention. Therefore, the reactivity between the carbon material and the electrolytic solution can be reduced, and battery characteristics represented by the cycle characteristics of the electricity storage device can be improved.
  • the electricity storage device of the present invention is not particularly limited, but non-aqueous electrolyte primary battery, aqueous electrolyte primary battery, non-aqueous electrolyte secondary battery, aqueous electrolyte secondary battery, all-solid electrolyte primary battery, all solid Examples include an electrolyte secondary battery, a capacitor, an electric double layer capacitor, and a lithium ion capacitor.
  • the secondary battery as an example of the electricity storage device of the present invention may be any battery using a compound that undergoes insertion and desorption reactions of alkali metal ions or alkaline earth metal ions.
  • alkali metal ions include lithium ions, sodium ions, and potassium ions.
  • alkaline earth metal ions include calcium ions and magnesium ions.
  • the present invention is highly effective for the positive electrode of a non-aqueous electrolyte secondary battery, and among them, it can be suitably used for those using lithium ions.
  • a non-aqueous electrolyte secondary battery using lithium ions hereinafter referred to as a lithium ion secondary battery
  • a lithium ion secondary battery a non-aqueous electrolyte secondary battery using lithium ions
  • the positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery may be in the form in which the same electrode is formed on both sides of the current collector, the form in which the positive electrode is formed on one side of the current collector and the negative electrode is formed on the other side That is, it may be a bipolar electrode.
  • the non-aqueous electrolyte secondary battery may be one obtained by winding or laminating a separator disposed between the positive electrode side and the negative electrode side.
  • the positive electrode, the negative electrode, and the separator contain a non-aqueous electrolyte that is responsible for lithium ion conduction.
  • the non-aqueous electrolyte secondary battery may be wound with a laminate film after the laminate is wound or laminated, or a metal having a square shape, an elliptical shape, a cylindrical shape, a coin shape, a button shape, or a sheet shape. It may be packaged with a can. The exterior may be provided with a mechanism for releasing the generated gas.
  • the number of stacked layers is not particularly limited, and the stacked body can be stacked until a desired voltage value and battery capacity are developed.
  • the non-aqueous electrolyte secondary battery can be an assembled battery connected in series or in parallel, depending on the desired size, capacity, and voltage.
  • a control circuit is attached to the assembled battery in order to confirm the state of charge of each battery and improve safety.
  • the non-aqueous electrolyte used for the non-aqueous electrolyte secondary battery is not particularly limited.
  • an electrolytic solution in which a solute is dissolved in a non-aqueous solvent can be used.
  • a gel electrolyte obtained by impregnating a polymer with an electrolyte solution in which a solute is dissolved in a nonaqueous solvent a solid polymer electrolyte such as polyethylene oxide or polypropylene oxide, or an inorganic solid electrolyte such as sulfide glass or oxynitride is used. Also good.
  • non-aqueous solvent it is preferable to include a cyclic aprotic solvent and / or a chain aprotic solvent because solutes described later are more easily dissolved.
  • cyclic aprotic solvent examples include cyclic carbonates, cyclic esters, cyclic sulfones, and cyclic ethers.
  • chain aprotic solvent examples include chain carbonate, chain carboxylic acid ester, chain ether and the like.
  • a solvent generally used as a solvent for nonaqueous electrolytes such as acetonitrile may be used. More specifically, dimethyl carbonate, methyl ethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, ⁇ -butyl lactone, 1,2-dimethoxyethane, sulfolane, dioxolane, propion For example, methyl acid can be used.
  • These solvents may be used alone, or two or more kinds of solvents may be mixed and used. However, it is preferable to use a solvent in which two or more kinds of solvents are mixed from the viewpoint of further easily dissolving a solute described later and further improving the conductivity of lithium ions.
  • the solute is not particularly limited, LiClO 4, LiBF 4, LiPF 6, LiAsF 6, LiCF 3 SO 3, LiBOB (Lithium Bis (Oxalato) Borate), or it is preferable to use a LiN (SO 2 CF 3) 2 . In this case, it can be dissolved more easily by a non-aqueous solvent.
  • the concentration of the solute contained in the electrolytic solution is preferably 0.5 mol / L or more and 2.0 mol / L or less. If the concentration of the solute is less than 0.5 mol / L, desired lithium ion conductivity may not be exhibited. On the other hand, if the concentration of the solute is higher than 2.0 mol / L, the solute may not dissolve further.
  • the nonaqueous electrolyte preferably contains the above-described electrolytic solution in which a solute is dissolved in a nonaqueous solvent and a compound that reacts with Li / Li + at 0.0 V or more and 2.0 V or less.
  • a protective film can be formed on the surface of the negative electrode, thereby further suppressing the intrusion of a substance that inhibits the charge / discharge reaction into the negative electrode. Therefore, the reaction between the electrolytic solution and the electrode material constituting the negative electrode can be further suppressed, and thereby the deterioration of the battery characteristics represented by the cycle characteristics of the nonaqueous electrolyte secondary battery can be further suppressed.
  • a compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + can be used as an additive for forming a negative electrode film.
  • the content of the compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + is preferably 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte. .
  • content of a compound exists in the said range deterioration of the battery characteristic by reaction with electrolyte solution and the electrode material which comprises a negative electrode can be suppressed further.
  • a compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + is not particularly limited.
  • vinylene carbonate, fluorinated ethylene carbonate, ethylene sulfite, 1,3-propane sultone, or Biphenyl and the like can be used.
  • the nonaqueous electrolyte contains the electrolyte solution which melt
  • a protective film can be formed on the surface of the positive electrode, thereby further suppressing the intrusion of a substance that inhibits the charge / discharge reaction into the positive electrode. Accordingly, it is possible to further suppress the reaction between the electrolytic solution and the electrode material constituting the positive electrode, thereby further suppressing the deterioration of the battery characteristics represented by the cycle characteristics of the nonaqueous electrolyte secondary battery.
  • a compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + can be used as an additive for forming a positive electrode film.
  • the content of the compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + is preferably 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte. .
  • content of a compound exists in the said range deterioration of the battery characteristic by reaction with electrolyte solution and the electrode material which comprises a positive electrode can be suppressed further.
  • the compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + is not particularly limited.
  • dinitrile compounds such as 1,2-dicyanoethane, phosphones represented by triethylphosphonoacetate, and the like.
  • Acid esters, cyclic acid anhydrides represented by succinic anhydride and maleic anhydride, and the like can be used.
  • the said compound may be used only by 1 type, and may be used in mixture of 2 or more types.
  • nonaqueous electrolyte may further contain additives such as a flame retardant and a stabilizer.
  • polyethylene glycol trade name “PG600” manufactured by Sanyo Chemical Industries, Ltd. was used.
  • homomixer model number “TKHOMOMIXER MARKII” manufactured by TOKUSHU KIKA Corporation was used.
  • the produced raw material composition was heat-treated at 150 ° C. to remove water. Thereafter, the composition from which water was removed was heat-treated at a temperature of 370 ° C. for 1 hour, thereby producing a carbon material in which a part of polyethylene glycol remained.
  • the produced carbon material is heat-treated at 420 ° C. for 0.5 hours (hereinafter, also referred to as “heat treatment A”) to obtain a carbon material having a graphite structure and partially exfoliated graphite. It was.
  • the obtained carbon material contained 3.0% by weight of resin with respect to the total weight.
  • the amount of resin was calculated as the amount of resin using TG (manufactured by Hitachi High-Tech Science Co., Ltd., product number “STA7300”) in the range of 200 ° C. to 600 ° C.
  • Example 2 A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 3 hours.
  • Example 3 A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 2 hours.
  • Example 4 A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 1.5 hours.
  • Example 5 A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 2.5 hours.
  • Example 6 A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 1 hour.
  • polyethylene glycol trade name “PG600” manufactured by Sanyo Chemical Industries, Ltd. was used.
  • homomixer model number “TKHOMOMIXER MARKII” manufactured by TOKUSHU KIKA Corporation was used.
  • the produced raw material composition was heat-treated at 150 ° C. to remove water. Thereafter, the composition from which water was removed was heat-treated at a temperature of 370 ° C. for 1 hour, thereby producing a carbon material in which a part of polyethylene glycol remained.
  • the produced carbon material was heat-treated at 420 ° C. in the order of 0.5 hours to obtain a carbon material having a graphite structure and partially exfoliated graphite.
  • the carbon material obtained in Comparative Example 1 contained 38.7 wt% resin with respect to the total weight.
  • Comparative Example 2 In Comparative Example 2, commercially available carbon black (manufactured by Denka Co., Ltd., trade name “Denka Black”) was used as it was as the carbon material.
  • Comparative Example 3 In Comparative Example 3, commercially available highly oriented pyrolytic graphite (HOPG) was used as it was as the carbon material.
  • HOPG highly oriented pyrolytic graphite
  • Examples 1 to 6 and Comparative Examples 1 to 3 were placed on a sample stage and installed in a measuring device (PHI5000 VersaProbeII) for X-ray photoelectron spectroscopy (XPS). Next, a photoelectron spectrum was measured under the conditions of X-ray source: AlK ⁇ , photoelectron extraction angle: 45 degrees, and X-ray beam diameter of 200 ⁇ m (50 W, 15 kV).
  • the ratio of the number of carbon atoms to the number of oxygen atoms contained in the carbon material is determined by dividing the peak area of the C1s spectrum appearing in the binding energy: 280 eV to 292 eV by the peak area of the O1s spectrum appearing in the binding energy: 525 eV to 540 eV (C / O ratio) was calculated.
  • the working electrode was prepared by the following procedure. First, each carbon material (4.0 g) of Examples 1 to 6 and Comparative Examples 1 to 3 and a powder of polytetrafluoroethylene as a binder (hereinafter PTFE, 6-J, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) ) was mixed in an agate mortar for 5 minutes to prepare a mixed powder. Next, the mixed powder was sandwiched between aluminum foils (thickness 20 ⁇ m, single-sided gloss, manufactured by UACJ), and then pressed with a roll press machine (roll gap 100 ⁇ m, manufactured by Tester Sangyo Co., Ltd.) to obtain a sheet-like mixture. . Finally, the working electrode was produced by cutting the sheet-like mixture into a size of 10 mm ⁇ . The weight and thickness of the working electrode were 10 mg and 100 ⁇ m, respectively.
  • PTFE polytetrafluoroethylene as a binder
  • the tripolar cell was produced as follows.
  • the working electrode was installed at the working electrode location of a three-electrode cell (HS three-pole cell, Hosen Co., Ltd.).
  • a separator polyolefin-based microporous film, 25 ⁇ m, 24 mm ⁇
  • Li metal (16 mm ⁇ ) was installed as a counter electrode at a counter electrode installation location.
  • Li metal inner diameter: 16 mm ⁇ , outer diameter: 25 mm ⁇
  • Cyclic voltammetry measurement was performed as follows.
  • the evaluation cell was connected to an electrochemical measurement device (Biologic) and left for 3 hours.
  • the potential was swept within a sweep rate (1 mV / s) and a sweep range of 2.5 V to 4.5 V. This sweep was repeated 10 times at room temperature of 25 ° C. ⁇ 5 ° C.
  • the current value 4.25 V at the time of the first sweep to the noble potential side and dividing by the weight of the carbon material contained in the electrode, the current resulting from the reaction between the carbon material and the electrolyte solution The value was calculated.
  • the battery characteristics were evaluated by producing a nonaqueous electrolyte secondary battery as follows.
  • LiCo 1/3 Ni 1/3 Mn 1/3 O 2 as a positive electrode active material is described in non-patent literature (Journal of PowerSources, Vol. 146, pp. 636-639 (2005)). It was produced by the method.
  • lithium hydroxide was mixed with ternary hydroxide having a molar ratio of cobalt, nickel and manganese of 1: 1: 1 to obtain a mixture.
  • this mixture was heated at 1000 ° C. in an air atmosphere to prepare a positive electrode active material.
  • the dispersion of the positive electrode active material was dropped into the dispersion of the carbon material with a dropper.
  • the dispersion liquid of the carbon material was continuously treated with an ultrasonic cleaning machine (manufactured by AS ONE). Thereafter, the mixed liquid of the dispersion was stirred with a magnetic stirrer for 3 hours.
  • the mixed liquid of the dispersion was subjected to suction filtration, and then vacuum-dried at 110 ° C. for 1 hour to prepare a composite of the positive electrode active material and the carbon material (active material-carbon material composite).
  • the amount necessary for the production of the positive electrode was produced by repeating the above steps.
  • 96 parts by weight of the composite was mixed with a binder (PVdF, solid content concentration of 12% by weight, NMP solution) so that the solid content was 4 parts by weight to prepare a slurry.
  • PVdF solid content concentration of 12% by weight, NMP solution
  • this slurry was applied to an aluminum foil (20 ⁇ m), then heated in a blast oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours.
  • the slurry was applied and dried on the back surface of the aluminum foil in the same manner.
  • the capacity of the positive electrode was calculated from the electrode weight per unit area and the theoretical capacity (150 mAh / g) of the positive electrode active material. As a result, the capacity of the positive electrode (per one surface) was 5 mAh / cm 2 .
  • the negative electrode was produced as follows.
  • the negative electrode active material artificial graphite
  • a binder PVdF, solid content concentration: 12% by weight, NMP solution
  • the slurry was applied to a copper foil (20 ⁇ m), heated in a blowing oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours.
  • the slurry was applied and dried on the back surface of the copper foil in the same manner.
  • the capacity of the negative electrode was calculated from the weight of the electrode per unit area and the theoretical capacity (350 mAh / g) of the negative electrode active material. As a result, the capacity (per side) of the negative electrode was 6.0 mAh / cm 2 .
  • the produced positive electrode (electrode part: 40 mm ⁇ 50 mm), negative electrode (electrode part: 45 mm ⁇ 55 mm) and separator (polyolefin-based microporous membrane, 25 ⁇ m, 50 mm ⁇ 60 mm) were prepared as negative electrode / separator / positive electrode / separator / In order of the negative electrode, the layers were stacked so that the capacity of the positive electrode was 200 mAh (one positive electrode and two negative electrodes).
  • the steps so far were performed in an atmosphere (dry box) having a dew point of ⁇ 40 ° C. or lower.
  • the battery is left at 25 ° C. for 100 hours, and the gas generated in an atmosphere (dry box) with a dew point of ⁇ 40 ° C. or less and excessive electrolysis
  • the nonaqueous electrolyte secondary battery was produced by sealing again while reducing the pressure.
  • the cycle characteristics were evaluated by the following method. First, the produced nonaqueous electrolyte secondary battery was placed in a 45 ° C. thermostat and connected to a charge / discharge device (HJ1005SD8, manufactured by Hokuto Denko). Next, constant current constant voltage charge (current value: 20 mA, charge end voltage: 4.25 V, constant voltage discharge voltage: 4.25 V, constant voltage discharge end condition: 3 hours elapsed, or current value 4 mA), constant current discharge A cycle operation in which (current value: 100 mA, discharge end voltage: 2.5 V) was repeated 300 times was performed. Finally, the discharge capacity retention rate (cycle characteristics) was calculated by calculating the ratio of the 300th discharge capacity when the first discharge capacity was 100. The cycle characteristics were evaluated according to the following evaluation criteria.
  • Example 7 a nonaqueous electrolyte secondary battery was produced and evaluated as follows.
  • LiCo 1/3 Ni 1/3 Mn 1/3 O 2 as a positive electrode active material is described in non-patent literature (Journal of PowerSources, Vol. 146, pp. 636-639 (2005)). It was produced by the method.
  • lithium hydroxide was mixed with ternary hydroxide having a molar ratio of cobalt, nickel and manganese of 1: 1: 1 to obtain a mixture.
  • this mixture was heated at 1000 ° C. in an air atmosphere to prepare a positive electrode active material.
  • the dispersion of the positive electrode active material was dropped into the dispersion of the carbon material with a dropper.
  • the dispersion liquid of the carbon material was continuously treated with an ultrasonic cleaning machine (manufactured by AS ONE). Thereafter, the mixed liquid of the dispersion was stirred with a magnetic stirrer for 3 hours.
  • the mixed liquid of the dispersion was subjected to suction filtration, and then vacuum-dried at 110 ° C. for 1 hour to prepare a composite of the positive electrode active material and the carbon material (active material-carbon material composite).
  • the amount necessary for the production of the positive electrode was produced by repeating the above steps.
  • 96 parts by weight of the composite was mixed with a binder (PVdF, solid content concentration of 12% by weight, NMP solution) so that the solid content was 4 parts by weight to prepare a slurry.
  • PVdF solid content concentration of 12% by weight, NMP solution
  • this slurry was applied to an aluminum foil (20 ⁇ m), then heated in a blast oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours.
  • the slurry was applied and dried on the back surface of the aluminum foil in the same manner.
  • the capacity of the positive electrode was calculated from the electrode weight per unit area and the theoretical capacity (150 mAh / g) of the positive electrode active material. As a result, the capacity of the positive electrode (per one surface) was 5 mAh / cm 2 .
  • the negative electrode was produced as follows.
  • the negative electrode active material artificial graphite
  • a binder PVdF, solid content concentration: 12% by weight, NMP solution
  • the slurry was applied to a copper foil (20 ⁇ m), heated in a blowing oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours.
  • the slurry was applied and dried on the back surface of the copper foil in the same manner.
  • the capacity of the negative electrode was calculated from the weight of the electrode per unit area and the theoretical capacity (350 mAh / g) of the negative electrode active material. As a result, the capacity (per side) of the negative electrode was 6.0 mAh / cm 2 .
  • the positive electrode (electrode portion: 40 mm ⁇ 50 mm), negative electrode (electrode portion: 45 mm ⁇ 55 mm) and separator (polyolefin-based microporous membrane, 25 ⁇ m, 50 mm ⁇ 60 mm) prepared as described above were used as the negative electrode / separator.
  • the layers were laminated in the order of / positive electrode / separator / negative electrode so that the capacity of the positive electrode was 200 mAh (one positive electrode and two negative electrodes).
  • the steps so far were performed in an atmosphere (dry box) with a dew point of ⁇ 40 ° C. or lower.
  • the battery is left at 25 ° C. for 100 hours, and the gas generated in an atmosphere (dry box) with a dew point of ⁇ 40 ° C. or less and excessive electrolysis
  • the nonaqueous electrolyte secondary battery was produced by sealing again while reducing the pressure.
  • Example 8 A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 7 except that the nonaqueous electrolyte prepared as follows was used as the nonaqueous electrolyte.
  • the cycle characteristics of the nonaqueous electrolyte secondary batteries produced in Example 7 and Example 8 were evaluated by the following method. First, the produced nonaqueous electrolyte secondary battery was placed in a 45 ° C. thermostat and connected to a charge / discharge device (HJ1005SD8, manufactured by Hokuto Denko). Next, constant current constant voltage charge (current value: 20 mA, charge end voltage: 4.25 V, constant voltage discharge voltage: 4.25 V, constant voltage discharge end condition: 3 hours elapsed, or current value 4 mA), constant current discharge A cycle operation in which (current value: 100 mA, discharge end voltage: 2.5 V) was repeated 300 times was performed. Finally, the discharge capacity retention rate (cycle characteristics) was calculated by calculating the ratio of the 300th discharge capacity when the first discharge capacity was 100. The cycle characteristics were evaluated according to the following evaluation criteria.

Abstract

Provided is a carbon material which is capable of enhancing battery characteristics as typified by cycle characteristics of an electricity storage device. A carbon material which has a graphene multilayer structure, and which is configured such that: in the X-ray diffraction spectroscopy of a mixture of the carbon material and Si at a weight ratio of 1:1, the ratio of the maximum peak height a within the 2θ range of from 24° (inclusive) to 28° (exclusive) to the maximum peak height b within the 2θ range of from 28° (inclusive) to 30° (exclusive), namely the ratio a/b is from 0.2 (inclusive) to 10.0 (inclusive); and the absolute value of the current value at the potential of 4.25 V (vs. Li+/Li) is from 0.001 A/g (inclusive) to 0.02 A/g (inclusive) as determined by cyclic voltammetry with use of an electrolyte solution which contains LiPF6 having a concentration of 1 mol/L and a mixed solution that contains ethylene carbonate and dimethyl carbonate at a volume ratio of 1:2, while using an electrode that contains the carbon material as the working electrode and using lithium metal as the reference electrode and the counter electrode.

Description

炭素材料、蓄電デバイス用電極、蓄電デバイス、及び非水電解質二次電池Carbon material, electrode for power storage device, power storage device, and nonaqueous electrolyte secondary battery
　本発明は、グラフェン積層構造を有する炭素材料、並びに該炭素材料を用いた蓄電デバイス用電極、蓄電デバイス及び非水電解質二次電池に関する。 The present invention relates to a carbon material having a graphene laminated structure, and an electrode for an electricity storage device, an electricity storage device, and a nonaqueous electrolyte secondary battery using the carbon material.
　近年、携帯機器、ハイブリッド自動車、電気自動車、家庭用蓄電用途等に向けて、蓄電デバイスの研究開発が盛んに行われている。 In recent years, research and development of power storage devices have been actively conducted for portable devices, hybrid vehicles, electric vehicles, household power storage applications, and the like.
　例えば、下記の特許文献１には、集電体上に活物質層が設けられてなる正極を備える、非水電解質二次電池が開示されている。特許文献１の非水電解質二次電池における正極の活物質層は、複数の活物質粒子と、炭素材料としてのグラフェンとを含んでいる。特許文献１では、このグラフェンの酸素濃度が、２原子％以上、２０原子％以下であることが記載されている。 For example, Patent Document 1 below discloses a nonaqueous electrolyte secondary battery including a positive electrode in which an active material layer is provided on a current collector. The active material layer of the positive electrode in the nonaqueous electrolyte secondary battery of Patent Document 1 includes a plurality of active material particles and graphene as a carbon material. Patent Document 1 describes that the oxygen concentration of this graphene is 2 atomic% or more and 20 atomic% or less.
　また、下記の特許文献２には、炭素材料と活物質とを含む電極を備える、リチウムイオン二次電池が開示されている。特許文献２では、上記炭素材料の一例として、部分的にグラファイトが剥離されている構造を有する、炭素材料が開示されている。 Also, Patent Document 2 below discloses a lithium ion secondary battery including an electrode including a carbon material and an active material. Patent Document 2 discloses a carbon material having a structure in which graphite is partially exfoliated as an example of the carbon material.
特開２０１７－１８３２９２号公報JP 2017-183292 A 特開２０１７－２１６２５４号公報JP 2017-216254 A
　しかしながら、特許文献１や特許文献２に記載の炭素材料を蓄電デバイス、特に非水電解質二次電池に用いた場合、所望のサイクル特性を得られない場合があった。 However, when the carbon materials described in Patent Document 1 and Patent Document 2 are used in power storage devices, particularly non-aqueous electrolyte secondary batteries, desired cycle characteristics may not be obtained.
　本発明の目的は、蓄電デバイスのサイクル特性に代表される電池特性を高め得る、炭素材料、並びに該炭素材料を用いた蓄電デバイス用電極、蓄電デバイス及び非水電解質二次電池を提供することにある。 An object of the present invention is to provide a carbon material, an electrode for an electricity storage device using the carbon material, an electricity storage device, and a nonaqueous electrolyte secondary battery that can improve battery characteristics represented by the cycle characteristics of the electricity storage device. is there.
　本発明に係る炭素材料の広い局面では、グラフェン積層構造を有する炭素材料であって、前記炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さａと、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さｂとの比ａ／ｂが、０．２以上、１０．０以下であり、前記炭素材料が含まれる電極を作用電極とし、リチウム金属を参照電極及び対極とし、１ｍｏｌ／Ｌ濃度のＬｉＰＦ６と、エチレンカーボネートとジメチルカーボネートとの体積比１：２における混合溶液とを含む電解液を用いて、サイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流値の絶対値が、０．００１Ａ／ｇ以上、０．０２Ａ／ｇ以下である。 In a wide aspect of the carbon material according to the present invention, when measuring an X-ray diffraction spectrum of a carbon material having a graphene laminated structure in a weight ratio of 1: 1 between the carbon material and Si, 2θ is The ratio a / b between the highest peak height a in the range of 24 ° or more and less than 28 ° and the highest peak height b in the range of 2θ of 28 ° or more and less than 30 ° is 0.2 The volume ratio of LiPF 6 having a concentration of 1 mol / L and ethylene carbonate to dimethyl carbonate is 1:10, which is 10.0 or less and the electrode containing the carbon material is a working electrode, lithium metal is a reference electrode and a counter electrode. using an electrolytic solution containing a mixed solution of 2, the absolute value of the current value in the potential of 4.25V as measured by cyclic voltammetry (vs.Li + / Li) is 0. 01A / g or more, it is less than or equal to 0.02A / g.
　本発明に係る炭素材料の他の広い局面では、グラフェン積層構造を有する炭素材料であって、前記炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さａと、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さｂとの比ａ／ｂが、０．２以上、１０．０以下であり、前記炭素材料の元素分析により測定された酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）が、２０以上、２００以下である。 In another broad aspect of the carbon material according to the present invention, when the X-ray diffraction spectrum of the carbon material having a graphene laminated structure in a weight ratio of 1: 1 between the carbon material and Si is measured, 2θ However, the ratio a / b between the highest peak height a in the range of 24 ° or more and less than 28 ° and the highest peak height b in the range of 2θ of 28 ° or more and less than 30 ° is 0 The ratio of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less.
　本発明に係る炭素材料のある特定の局面では、前記炭素材料が、薄片化黒鉛である。 In a specific aspect of the carbon material according to the present invention, the carbon material is exfoliated graphite.
　本発明に係る炭素材料の他の特定の局面では、前記炭素材料が、蓄電デバイス用電極に用いられる。 In another specific aspect of the carbon material according to the present invention, the carbon material is used for an electrode for an electricity storage device.
　本発明に係る蓄電デバイス用電極は、本発明に従って構成される炭素材料を含む。 The electrode for an electricity storage device according to the present invention includes a carbon material configured according to the present invention.
　本発明に係る蓄電デバイスは、本発明に従って構成される蓄電デバイス用電極を備える。 An electricity storage device according to the present invention includes an electrode for an electricity storage device configured according to the present invention.
　本発明に係る非水電解質二次電池は、本発明に従って構成される蓄電デバイス用電極と、非水電解質とを備える。 A non-aqueous electrolyte secondary battery according to the present invention includes an electrode for an electricity storage device configured according to the present invention and a non-aqueous electrolyte.
　本発明に係る非水電解質二次電池のある特定の局面では、前記非水電解質が、非水溶媒に溶質を溶解させた電解液と、Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物とを含み、前記化合物の含有量が、前記非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下である。 In a specific aspect of the non-aqueous electrolyte secondary battery according to the present invention, the non-aqueous electrolyte is an electrolytic solution in which a solute is dissolved in a non-aqueous solvent, and 0.0 V or more with respect to Li / Li + . A compound that reacts at 0 V or less, and the content of the compound is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte.
　本発明に係る非水電解質二次電池の他の特定の局面では、前記非水電解質が、非水溶媒に溶質を溶解させた電解液と、Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物とを含み、前記化合物の含有量が、前記非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下である。 In another specific aspect of the non-aqueous electrolyte secondary battery according to the present invention, the non-aqueous electrolyte is 2.0 V or higher with respect to an electrolytic solution obtained by dissolving a solute in a non-aqueous solvent, and Li / Li + . The compound reacts at 0.0 V or less, and the content of the compound is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the non-aqueous electrolyte.
　本発明によれば、蓄電デバイスのサイクル特性に代表される電池特性を高め得る、炭素材料、並びに該炭素材料を用いた蓄電デバイス用電極、蓄電デバイス及び非水電解質二次電池を提供することができる。 According to the present invention, it is possible to provide a carbon material, an electrode for an electricity storage device using the carbon material, an electricity storage device, and a nonaqueous electrolyte secondary battery that can improve battery characteristics represented by the cycle characteristics of the electricity storage device. it can.
　以下、本発明の詳細を説明する。 Hereinafter, the details of the present invention will be described.
　本発明の蓄電デバイスとしては、特に限定されないが、非水電解質一次電池、水系電解質一次電池、非水電解質二次電池、水系電解質二次電池、全固体電解質一次電池、全固体電解質二次電池、コンデンサ、電気二重層キャパシタ、又はリチウムイオンキャパシタなどが例示される。本発明の炭素材料は、上記のような蓄電デバイス用の電極に含まれる電極材料である。また、本発明の蓄電デバイス用電極は、上記のような蓄電デバイスに用いられる電極である。 The power storage device of the present invention is not particularly limited, but a non-aqueous electrolyte primary battery, an aqueous electrolyte primary battery, a non-aqueous electrolyte secondary battery, an aqueous electrolyte secondary battery, an all-solid electrolyte primary battery, an all-solid electrolyte secondary battery, Examples thereof include a capacitor, an electric double layer capacitor, and a lithium ion capacitor. The carbon material of the present invention is an electrode material included in the electrode for an electricity storage device as described above. The electrode for an electricity storage device of the present invention is an electrode used for the above electricity storage device.
　［炭素材料］
　本発明の炭素材料は、蓄電デバイス用の電極に含まれる炭素材料である。上記炭素材料は、グラフェン積層構造を有する炭素材料を含む。上記炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さａと、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さｂとの比ａ／ｂが、０．２以上、１０．０以下である。 [Carbon material]
The carbon material of the present invention is a carbon material contained in an electrode for an electricity storage device. The carbon material includes a carbon material having a graphene stacked structure. When the X-ray diffraction spectrum of the mixture of the carbon material and Si at a weight ratio of 1: 1 was measured, 2θ was the highest peak height a in the range of 24 ° or more and less than 28 °, and 2θ was The ratio a / b with the height b of the highest peak in the range of 28 ° or more and less than 30 ° is 0.2 or more and 10.0 or less.
　第１の発明においては、上記炭素材料が含まれる電極を作用電極に用いて、サイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流値の絶対値が、０．００１Ａ／ｇ以上、０．０２Ａ／ｇ以下である。 In the first invention, the absolute value of the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry using the electrode containing the carbon material as a working electrode is 0.00. It is 001 A / g or more and 0.02 A / g or less.
　本願発明者らは、サイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流値が、炭素材料と電解液との反応性が相関することを見出した。すなわち、サイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流値を上記の範囲内とすることで、炭素材料と電解液との反応性を小さくすることができ、その結果サイクル特性に代表される蓄電デバイスの電池特性を高め得ることを見出した。 The inventors of the present application have found that the reactivity between the carbon material and the electrolytic solution correlates with the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry. That is, by setting the current value at a potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry within the above range, the reactivity between the carbon material and the electrolytic solution can be reduced. As a result, it has been found that the battery characteristics of an electricity storage device represented by cycle characteristics can be improved.
　また、第２の発明においては、上記炭素材料の元素分析により測定された酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）は、２０以上、２００以下である。Ｃ／Ｏ比が上記下限以上である場合、炭素材料と電解液との反応性を低めることができる。これは、電極中に含まれる酸素原子の量が少なくなり、それによって電解液との反応をより一層抑制できているためであると考えられる。また、その反応生成物が減少することにより対極への悪影響をより一層低減できるものと考えられる。その結果、サイクル特性に代表される電池特性をより一層高めることができているものと考えられる。また、Ｃ／Ｏ比が、上記上限以下である場合、電子伝導経路を形成し易くすることができ、レート特性を高めることができる。 In the second invention, the ratio of the number of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less. When the C / O ratio is not less than the above lower limit, the reactivity between the carbon material and the electrolytic solution can be reduced. This is considered to be because the amount of oxygen atoms contained in the electrode is reduced, thereby further suppressing the reaction with the electrolytic solution. Moreover, it is thought that the adverse effect on the counter electrode can be further reduced by reducing the reaction product. As a result, it is considered that battery characteristics represented by cycle characteristics can be further improved. Further, when the C / O ratio is less than or equal to the above upper limit, an electron conduction path can be easily formed, and rate characteristics can be improved.
　本発明において、グラフェン積層構造を有する炭素材料としては、例えば、黒鉛又は薄片化黒鉛などが挙げられる。 In the present invention, examples of the carbon material having a graphene laminated structure include graphite and exfoliated graphite.
　黒鉛とは、複数のグラフェンシートの積層体である。黒鉛のグラフェンシートの積層数は、通常、１０万層～１００万層程度である。黒鉛としては、例えば、天然黒鉛、人造黒鉛又は膨張黒鉛などを用いることができる。膨張黒鉛は、通常の黒鉛よりもグラフェン層同士の層間距離が大きくなっている割合が高く、電解液の保液性をより一層高く保つ可能性があることから、好ましい。 Graphite is a laminate of a plurality of graphene sheets. The number of graphite graphene sheets laminated is usually about 100,000 to 1,000,000. As the graphite, for example, natural graphite, artificial graphite or expanded graphite can be used. Expanded graphite is preferable because the ratio of the distance between the graphene layers is larger than that of normal graphite, and the liquid retaining property of the electrolytic solution may be further increased.
　薄片化黒鉛とは、元の黒鉛を剥離処理して得られるものであり、元の黒鉛よりも薄いグラフェンシート積層体をいう。薄片化黒鉛におけるグラフェンシートの積層数は、元の黒鉛より少なければよい。なお、薄片化黒鉛は、酸化薄片化黒鉛であってもよい。 Exfoliated graphite refers to a graphene sheet laminate that is obtained by exfoliating the original graphite and is thinner than the original graphite. The number of graphene sheets laminated in exfoliated graphite should be less than the original graphite. The exfoliated graphite may be oxidized exfoliated graphite.
　薄片化黒鉛において、グラフェンシートの積層数は、特に限定されないが、好ましくは２層以上、より好ましくは５層以上、好ましくは１０００層以下、より好ましくは５００層以下である。グラフェンシートの積層数が上記下限以上である場合、薄片化黒鉛の導電性をより一層高めることができる。グラフェンシートの積層数が上記上限以下である場合、薄片化黒鉛の比表面積をより一層大きくすることができる。 In the exfoliated graphite, the number of laminated graphene sheets is not particularly limited, but is preferably 2 layers or more, more preferably 5 layers or more, preferably 1000 layers or less, more preferably 500 layers or less. When the number of graphene sheets stacked is not less than the above lower limit, the conductivity of exfoliated graphite can be further enhanced. When the number of graphene sheets stacked is not more than the above upper limit, the specific surface area of exfoliated graphite can be further increased.
　また、薄片化黒鉛は、部分的にグラファイトが剥離されている構造を有する部分剥離型薄片化黒鉛であることが好ましい。 The exfoliated graphite is preferably partially exfoliated graphite having a structure in which the graphite is partially exfoliated.
　「部分的にグラファイトが剥離されている」構造の一例としては、グラフェンの積層体において、端縁からある程度内側までグラフェン層間が開いており、すなわち端縁にてグラファイトの一部が剥離しており、中央側の部分ではグラファイト層が元の黒鉛又は一次薄片化黒鉛と同様に積層していることをいうものである。従って、端縁にてグラファイトの一部が剥離している部分は、中央側の部分に連なっている。さらに、部分剥離型薄片化黒鉛には、端縁のグラファイトが剥離され薄片化したものが含まれていてもよい。 As an example of the “partially exfoliated graphite” structure, in the graphene laminate, the graphene layer is open from the edge to some extent, that is, a part of the graphite is exfoliated at the edge. In the central part, the graphite layer is laminated similarly to the original graphite or primary exfoliated graphite. Therefore, the part where the graphite is partially peeled off at the edge is continuous with the central part. Further, the partially exfoliated exfoliated graphite may include one obtained by exfoliating the edge graphite.
　部分剥離型薄片化黒鉛は、中央側の部分において、グラファイト層が元の黒鉛又は一次薄片化黒鉛と同様に積層している。そのため、従来の酸化グラフェンやカーボンブラックより黒鉛化度が高く、導電性に優れている。また、部分的にグラファイトが剥離されている構造を有することから、比表面積が大きい。そのため、活物質と接触する部分の面積を大きくすることができる。従って、部分剥離型薄片化黒鉛を含む蓄電デバイス用電極材料は、二次電池などの蓄電デバイスの電極に用いたときに、蓄電デバイスの抵抗をより一層小さくすることができるので、大電流での充放電時における発熱をより一層抑制することもできる。 In the partially exfoliated exfoliated graphite, the graphite layer is laminated at the center side in the same manner as the original graphite or primary exfoliated graphite. Therefore, the degree of graphitization is higher than that of conventional graphene oxide and carbon black, and the conductivity is excellent. Moreover, since it has a structure in which graphite is partially peeled off, the specific surface area is large. As a result, the area of the portion in contact with the active material can be increased. Therefore, when the electrode material for an electricity storage device containing partially exfoliated graphite is used for an electrode of an electricity storage device such as a secondary battery, the resistance of the electricity storage device can be further reduced, Heat generation during charging / discharging can be further suppressed.
　部分剥離型薄片化黒鉛は、例えば、黒鉛または一次薄片化黒鉛と、樹脂とを含み、樹脂が黒鉛または一次薄片化黒鉛にグラフトまたは吸着により固定されている組成物を用意し、該組成物中に含まれている樹脂を、熱分解することにより得ることができる。なお、樹脂を熱分解させる際には、樹脂の一部を残存させながら熱分解してもよいし、樹脂を完全に熱分解してもよい。 The partially exfoliated graphite includes, for example, graphite or primary exfoliated graphite and a resin, and a composition in which the resin is fixed to the graphite or primary exfoliated graphite by grafting or adsorption is prepared. Can be obtained by thermal decomposition. When the resin is thermally decomposed, it may be thermally decomposed while leaving a part of the resin, or the resin may be completely thermally decomposed.
　部分剥離型薄片化黒鉛は、例えば、国際公開第２０１４／０３４１５６号に記載の薄片化黒鉛・樹脂複合材料の製造方法と同様の方法で製造することができる。また、黒鉛としては、より一層容易にグラファイトを剥離することが可能であるため膨張黒鉛を使用することが好ましい。 The partially exfoliated exfoliated graphite can be produced by, for example, the same method as the exfoliated graphite / resin composite material described in International Publication No. 2014/034156. Further, as graphite, it is preferable to use expanded graphite because it can be more easily peeled off.
　また、一次薄片化黒鉛とは、各種方法により黒鉛を剥離することにより得られた薄片化黒鉛を広く含むものとする。一次薄片化黒鉛は、部分剥離型薄片化黒鉛であってもよい。一次薄片化黒鉛は、黒鉛を剥離することにより得られるものであるため、その比表面積は、黒鉛よりも大きいものであればよい。 Further, primary exfoliated graphite widely includes exfoliated graphite obtained by exfoliating graphite by various methods. The primary exfoliated graphite may be partially exfoliated graphite. Since primary exfoliated graphite is obtained by exfoliating graphite, the specific surface area may be larger than that of graphite.
　上記樹脂の熱分解における加熱の温度としては、樹脂の種類にもより特に限定されないが、例えば、２５０℃～１０００℃とすることができる。加熱時間としては、例えば、２０分～５時間とすることができる。また、上記加熱は、大気中で行ってもよく、窒素ガスなどの不活性ガス雰囲気下で行ってもよい。もっとも、上述した炭素材料と電解液との反応性をより一層小さくする観点からは、上記加熱を窒素ガスなどの不活性ガス雰囲気下で行うことが望ましい。 The heating temperature in the thermal decomposition of the resin is not particularly limited depending on the type of the resin, but may be, for example, 250 ° C. to 1000 ° C. The heating time can be, for example, 20 minutes to 5 hours. Moreover, the said heating may be performed in air | atmosphere and you may carry out in inert gas atmosphere, such as nitrogen gas. However, from the viewpoint of further reducing the reactivity between the carbon material and the electrolytic solution described above, it is desirable to perform the heating in an inert gas atmosphere such as nitrogen gas.
　樹脂としては、特に限定されないが、ラジカル重合性モノマーの重合体であることが好ましい。この場合、１種のラジカル重合性モノマーの単独重合体であってもよく、複数種のラジカル重合性モノマーの共重合体であってもよい。ラジカル重合性モノマーは、ラジカル重合性の官能基を有するモノマーである限り、特に限定されない。 The resin is not particularly limited, but is preferably a polymer of a radical polymerizable monomer. In this case, it may be a homopolymer of one kind of radically polymerizable monomer or a copolymer of plural kinds of radically polymerizable monomers. The radical polymerizable monomer is not particularly limited as long as it is a monomer having a radical polymerizable functional group.
　ラジカル重合性モノマーとしては、例えば、スチレン、α－エチルアクリル酸メチル、α－ベンジルアクリル酸メチル、α－［２，２－ビス（カルボメトキシ）エチル］アクリル酸メチル、イタコン酸ジブチル、イタコン酸ジメチル、イタコン酸ジシクロヘキシル、α－メチレン－δ－バレロラクトン、α－メチルスチレン、α－アセトキシスチレンからなるα－置換アクリル酸エステル、グリシジルメタクリレート、３，４－エポキシシクロヘキシルメチルメタアクリレート、ヒドロキシエチルメタクリレート、ヒドロキシエチルアクリレート、ヒドロキシプロピルアクリレート、４－ヒドロキシブチルメタクリレートなどのグリシジル基や水酸基を持つビニルモノマー；アリルアミン、ジエチルアミノエチル（メタ）アクリレート、ジメチルアミノエチル（メタ）アクリレートのようなアミノ基を有するビニルモノマー、メタクリル酸、無水マレイン酸、マレイン酸、イタコン酸、アクリル酸、クロトン酸、２－アクリロイルオキシエチルサクシネート、２－メタクリロイルオキシエチルサクシネート、２－メタクリロイロキシエチルフタル酸などのカルボキシル基を有するモノマー；ユニケミカル社製、ホスマー（登録商標）Ｍ、ホスマー（登録商標）ＣＬ、ホスマー（登録商標）ＰＥ、ホスマー（登録商標）ＭＨ、ホスマー（登録商標）ＰＰなどのリン酸基を有するモノマー；ビニルトリメトキシシラン、３－メタクリロキシプロピルトリメトキシシランなどのアルコキシシリル基を有するモノマー；アルキル基やベンジル基などを有する（メタ）アクリレート系モノマーなどが挙げられる。 Examples of the radical polymerizable monomer include styrene, methyl α-ethyl acrylate, methyl α-benzyl acrylate, methyl α- [2,2-bis (carbomethoxy) ethyl] acrylate, dibutyl itaconate, dimethyl itaconate. , Itaconic acid dicyclohexyl, α-methylene-δ-valerolactone, α-methylstyrene, α-substituted acrylic acid ester consisting of α-acetoxystyrene, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, hydroxyethyl methacrylate, hydroxy Vinyl monomers having a glycidyl group or hydroxyl group such as ethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl methacrylate; allylamine, diethylaminoethyl (meth) acrylate, dimethyl Vinyl monomers having amino groups such as aminoethyl (meth) acrylate, methacrylic acid, maleic anhydride, maleic acid, itaconic acid, acrylic acid, crotonic acid, 2-acryloyloxyethyl succinate, 2-methacryloyloxyethyl succinate , Monomers having a carboxyl group such as 2-methacryloyloxyethylphthalic acid; manufactured by Unichemical, Phosmer (registered trademark) M, Phosmer (registered trademark) CL, Phosmer (registered trademark) PE, Phosmer (registered trademark) MH, Monomers having phosphate groups such as Phosmer (registered trademark) PP; Monomers having alkoxysilyl groups such as vinyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane; (meth) acrylates having alkyl groups, benzyl groups, etc. Monomer etc. And the like.
　用いられる樹脂の例としては、ポリエチレングリコール、ポリプロピレングリコール、ポリグリシジルメタクリレート、ポリ酢酸ビニル、ポリビニルブチラール（ブチラール樹脂）、又はポリ（メタ）アクリレート、ポリスチレンなどが挙げられる。 Examples of the resin used include polyethylene glycol, polypropylene glycol, polyglycidyl methacrylate, polyvinyl acetate, polyvinyl butyral (butyral resin), poly (meth) acrylate, and polystyrene.
　上記樹脂の中でも、好ましくはポリエチレングリコール、ポリプロピレングリコール、ポリ酢酸ビニルを用いることができる。ポリエチレングリコール、ポリプロピレングリコール、ポリ酢酸ビニルを用いた場合、部分剥離型薄片化黒鉛の比表面積をより一層大きくすることができる。なお、樹脂種は使用する溶媒との親和性を鑑み、適宜選定を行うことが可能である。 Among the above resins, polyethylene glycol, polypropylene glycol, and polyvinyl acetate can be preferably used. When polyethylene glycol, polypropylene glycol, or polyvinyl acetate is used, the specific surface area of the partially exfoliated exfoliated graphite can be further increased. The resin type can be appropriately selected in view of the affinity with the solvent used.
　黒鉛または一次薄片化黒鉛に固定されている熱分解前の樹脂の含有量は、樹脂分を除く黒鉛または一次薄片化黒鉛１００重量部に対し、好ましくは０．１重量部以上、より好ましくは０．５重量部以上、好ましくは３０００重量部以下、より好ましくは１０００重量部以下である。熱分解前の樹脂の含有量が上記範囲内である場合、熱分解後の残存樹脂の含有量をより一層制御しやすい。また、熱分解前の樹脂の含有量が上記上限値以下である場合、コスト的により一層有利である。 The content of the resin before pyrolysis fixed to graphite or primary exfoliated graphite is preferably 0.1 parts by weight or more, more preferably 0, per 100 parts by weight of graphite or primary exfoliated graphite excluding the resin component. 0.5 parts by weight or more, preferably 3000 parts by weight or less, more preferably 1000 parts by weight or less. When the content of the resin before pyrolysis is within the above range, it is easier to control the content of the residual resin after pyrolysis. Further, when the content of the resin before thermal decomposition is not more than the above upper limit value, it is more advantageous in terms of cost.
　熱分解後の残存樹脂の含有量は、樹脂分を含む部分剥離型薄片化黒鉛１００重量％に対し、０重量％以上、３０重量％以下であることが好ましく、０．５重量％以上、２５量％以下であることがより好ましく、１．０重量％以上、２０重量％以下であることがさらに好ましい。上記樹脂量が上記下限以上である場合、電極作製時のバインダー樹脂の添加量をより一層少なくすることができる。また、上記樹脂量が上記上限以下である場合、上述した炭素材料と電解液との反応性をより一層小さくすることができる。 The content of the residual resin after pyrolysis is preferably 0% by weight or more and 30% by weight or less with respect to 100% by weight of partially exfoliated exfoliated graphite including the resin component, and is 0.5% by weight or more, 25 The amount is more preferably at most%, more preferably at least 1.0% by weight and at most 20% by weight. When the amount of the resin is not less than the above lower limit, the amount of the binder resin added at the time of producing the electrode can be further reduced. Moreover, when the said resin amount is below the said upper limit, the reactivity of the carbon material mentioned above and electrolyte solution can be made still smaller.
　なお、熱分解前の樹脂の含有量及び部分剥離型薄片化黒鉛に残存している残存樹脂量は、例えば熱重量分析（以下、ＴＧ）によって加熱温度に伴う重量変化を測定し、算出することができる。 The resin content before thermal decomposition and the residual resin amount remaining in the partially exfoliated graphite can be calculated, for example, by measuring the weight change with the heating temperature by thermogravimetric analysis (hereinafter, TG). Can do.
　また、後述する正極活物質との複合体を作製する場合は、正極活物質との複合体を作製した後に、樹脂量を低減してもよく、樹脂を除去してもよい。 Further, when a composite with a positive electrode active material described later is manufactured, the amount of the resin may be reduced or the resin may be removed after preparing the composite with the positive electrode active material.
　上記樹脂量を低減又は上記樹脂を除去する方法としては、樹脂の分解温度以上、正極活物質の分解温度未満で加熱処理する方法が好ましい。この加熱処理は、大気中、不活性ガス雰囲気下、低酸素雰囲気下、又は真空下のいずれで行ってもよい。 As a method for reducing the resin amount or removing the resin, a method of performing a heat treatment at a temperature equal to or higher than the decomposition temperature of the resin and lower than the decomposition temperature of the positive electrode active material is preferable. This heat treatment may be performed in the air, in an inert gas atmosphere, in a low oxygen atmosphere, or in a vacuum.
　本発明においては、炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、ピーク比ａ／ｂが、０．２以上、好ましくは０．２２以上、より好ましくは０．２５以上である。また、ピーク比ａ／ｂは、１０．０以下、好ましくは８．０以下、より好ましくは５．０以下である。上記ａは、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さである。上記ｂは、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さである。なお、Ｓｉとしては、例えば、φ＝１００ｎｍ以下のシリコン粉末を用いることができる。 In the present invention, when the X-ray diffraction spectrum of the mixture of carbon material and Si at a weight ratio of 1: 1 is measured, the peak ratio a / b is 0.2 or more, preferably 0.22 or more, more preferably Is 0.25 or more. The peak ratio a / b is 10.0 or less, preferably 8.0 or less, and more preferably 5.0 or less. The a is the highest peak height in a range where 2θ is 24 ° or more and less than 28 °. The b is the highest peak height in a range where 2θ is 28 ° or more and less than 30 °. As Si, for example, silicon powder with φ = 100 nm or less can be used.
　上記Ｘ線回折スペクトルは、広角Ｘ線回折法によって測定することができる。Ｘ線としては、ＣｕＫα線（波長１．５４１Å）を用いることができる。Ｘ線回折装置としては、例えば、ＳｍａｒｔＬａｂ（リガク社製）を用いることができる。 The X-ray diffraction spectrum can be measured by a wide angle X-ray diffraction method. As X-rays, CuKα rays (wavelength 1.541Å) can be used. For example, SmartLab (manufactured by Rigaku Corporation) can be used as the X-ray diffraction apparatus.
　Ｘ線回折スペクトルにおいて、グラファイト構造に代表されるグラフェン積層構造に由来するピークは、２θ＝２６．４°付近に現れる。一方、シリコン粉末になどのＳｉに由来するピークは、２θ＝２８．５°付近に現れる。従って、上記比ａ／ｂは、２θ＝２６．４°付近のピークと２θ＝２８．５°付近のピークとのピーク比（２θ＝２６．４°付近のピーク／２θ＝２８．５°付近のピーク）により求めることができる。 In the X-ray diffraction spectrum, a peak derived from a graphene laminated structure represented by a graphite structure appears in the vicinity of 2θ = 26.4 °. On the other hand, a peak derived from Si, such as silicon powder, appears in the vicinity of 2θ = 28.5 °. Therefore, the ratio a / b is the peak ratio between the peak near 2θ = 26.4 ° and the peak near 2θ = 28.5 ° (peak near 2θ = 26.4 ° / 2θ = 28.5 °). Peak).
　なお、上記ａ／ｂが小さすぎると、炭素材料自身における黒鉛構造の形成が未熟であり、電子伝導性が低いことに加え、欠陥を有するので、正極や負極の抵抗値が増大し、電池特性が低下する場合がある。 If the a / b is too small, the formation of the graphite structure in the carbon material itself is immature, and in addition to low electronic conductivity, it has defects, so that the resistance value of the positive electrode and the negative electrode increases, and battery characteristics are increased. May decrease.
　上記ａ／ｂが大きすぎると、炭素材料自身が剛直となり、蓄電デバイスの正極や負極内に分散し難くなり、良好な電子伝導経路を形成しにくくなる場合がある。 If the above a / b is too large, the carbon material itself becomes rigid and difficult to disperse in the positive electrode or negative electrode of the electricity storage device, and it may be difficult to form a good electron conduction path.
　炭素材料が部分剥離型薄片化黒鉛の場合、上記ａ／ｂは、部分剥離型薄片化黒鉛を製造する際に熱分解を行うときの加熱条件や、黒鉛または一次薄片化黒鉛に固定されている熱分解前の樹脂の量により調整することができる。例えば、加熱温度を高くしたり、加熱時間を長くしたりすると、ａ／ｂを小さくすることができる。また、黒鉛または一次薄片化黒鉛に固定されている熱分解前の樹脂の量を少なくすると、ａ／ｂを小さくできる。 When the carbon material is partially exfoliated graphite, the above a / b is fixed to the heating conditions when pyrolyzing the partially exfoliated graphite, or to graphite or primary exfoliated graphite. It can adjust with the quantity of resin before thermal decomposition. For example, a / b can be reduced by increasing the heating temperature or increasing the heating time. Moreover, a / b can be reduced by reducing the amount of the resin before pyrolysis fixed to graphite or primary exfoliated graphite.
　第１の発明の炭素材料が含まれる電極を作用電極に用いて、サイクリックボルタンメトリーにより測定した、貴な電位側への掃印時における４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流の絶対値は、０．００１Ａ／ｇ以上、０．０２Ａ／ｇ以下である。電流の絶対値は、好ましくは０．００３Ａ／ｇ以上、より好ましくは０．００５Ａ／ｇ以上、好ましくは０．０１９Ａ／ｇ以下、より好ましくは０．０１８Ａ／ｇ以下である。 Current at a potential of 4.25 V (vs. Li + / Li) at the time of sweeping to the noble potential side, measured by cyclic voltammetry, using the electrode containing the carbon material of the first invention as a working electrode The absolute value of is 0.001 A / g or more and 0.02 A / g or less. The absolute value of the current is preferably 0.003 A / g or more, more preferably 0.005 A / g or more, preferably 0.019 A / g or less, more preferably 0.018 A / g or less.
　サイクリックボルタンメトリーでは、本発明の炭素材料が含まれる電極を作用電極とする。リチウム金属からなる電極を参照電極及び対極とする。また、１ｍｏｌ／Ｌ濃度のＬｉＰＦ６と、エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）との体積比１：２における混合溶液とを含む電解液を用いるものとする。 In cyclic voltammetry, an electrode containing the carbon material of the present invention is used as a working electrode. An electrode made of lithium metal is used as a reference electrode and a counter electrode. In addition, an electrolytic solution containing 1 mol / L concentration of LiPF 6 and a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1: 2 is used.
　このようにサイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流の絶対値が上記下限以上である場合、電子伝導経路をより一層形成し易くすることができ、レート特性をより一層高めることができる。また、上記電流の絶対値が上記上限以下である場合、炭素材料と電解液との反応性をより一層小さくすることができ、サイクル特性に代表される電池特性をより一層高めることができる。 Thus, when the absolute value of the current at the potential of 4.25 V (vs. Li + / Li) measured by cyclic voltammetry is equal to or more than the above lower limit, the electron conduction path can be more easily formed, and the rate The characteristics can be further enhanced. Moreover, when the absolute value of the said current is below the said upper limit, the reactivity of a carbon material and electrolyte solution can be made still smaller, and the battery characteristic represented by cycling characteristics can be improved further.
　なお、上記電流の絶対値は、上述の樹脂量を調整したり、上述の加熱条件を変更したり、上述の熱分解の際の加熱を不活性ガス雰囲気下で行ったりすることにより調整することができる。具体的には、例えば、炭素材料が部分剥離型薄片化黒鉛の場合、黒鉛または一次薄片化黒鉛に固定されている熱分解前の樹脂の量を少なくすると、電流の絶対値を小さくすることができる。また、上述の熱分解の際の加熱において、不活性ガスの濃度を高くし、酸素濃度を低くすると、電流の絶対値を小さくすることができる。 The absolute value of the current is adjusted by adjusting the amount of the resin described above, changing the heating conditions described above, or performing the heating during the pyrolysis described above in an inert gas atmosphere. Can do. Specifically, for example, when the carbon material is partially exfoliated graphite, reducing the amount of resin before pyrolysis fixed to graphite or primary exfoliated graphite can reduce the absolute value of the current. it can. Further, in the heating during the above-described thermal decomposition, the absolute value of the current can be reduced by increasing the concentration of the inert gas and decreasing the oxygen concentration.
　第２の発明において、上記炭素材料の元素分析により測定された酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）は、２０以上、２００以下である。炭素材料と電解液との反応性をより一層小さくし、サイクル特性をより一層向上させる観点から、上記Ｃ／Ｏ比は、より好ましくは２２以上、さらに好ましくは２５以上、より好ましくは１８０以下、さらに好ましくは１６０以下である。 In the second invention, the ratio of the number of carbon atoms to the number of oxygen atoms (C / O ratio) measured by elemental analysis of the carbon material is 20 or more and 200 or less. From the viewpoint of further reducing the reactivity between the carbon material and the electrolytic solution and further improving the cycle characteristics, the C / O ratio is more preferably 22 or more, further preferably 25 or more, more preferably 180 or less, More preferably, it is 160 or less.
　上記Ｃ／Ｏ比は、例えば、Ｘ線光電子分光法（ＸＰＳ）により、測定することができる。具体的には、Ｘ線源：ＡｌＫα、光電子取出角：４５度、Ｘ線ビーム径２００μｍ　（５０Ｗ１５ｋＶ）の条件で、光電子スペクトルを測定する。そして、Ｂｉｎｄｉｎｇ　Ｅｎｅｒｇｙ：２８０ｅＶ～２９２ｅＶに現れるＣ１ｓスペクトルのピーク面積を、Ｂｉｎｄｉｎｇ　Ｅｎｅｒｇｙ：５２５ｅＶ～５４０ｅＶに現れるＯ１ｓスペクトルのピーク面積で除する。それによって、炭素材料に含まれる酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）を算出することができる。また、上記Ｃ／Ｏ比は、上述の樹脂量を調整したり、上述の加熱条件を変更したり、上述の熱分解の際の加熱を不活性ガス雰囲気下で行ったりすることにより調整することができる。具体的には、例えば、炭素材料が部分剥離型薄片化黒鉛の場合、黒鉛または一次薄片化黒鉛に固定されている熱分解前の樹脂の量を少なくすると、上記Ｃ／Ｏ比を大きくすることができる。また、上述の熱分解の際の加熱において、不活性ガスの濃度を高くし、酸素濃度を低くすると、上記Ｃ／Ｏ比を大きくすることができる。 The C / O ratio can be measured by, for example, X-ray photoelectron spectroscopy (XPS). Specifically, the photoelectron spectrum is measured under the conditions of X-ray source: AlKα, photoelectron extraction angle: 45 degrees, and X-ray beam diameter of 200 μm (50 W 15 kV). Then, the peak area of the C1s spectrum appearing at Binding Energy: 280 eV to 292 eV is divided by the peak area of the O1s spectrum appearing at Binding Energy: 525 eV to 540 eV. Thereby, the ratio (C / O ratio) of the number of carbon atoms to the number of oxygen atoms contained in the carbon material can be calculated. The C / O ratio is adjusted by adjusting the amount of the resin, changing the heating condition, or performing the heating in the pyrolysis under an inert gas atmosphere. Can do. Specifically, for example, when the carbon material is partially exfoliated graphite, the C / O ratio is increased by reducing the amount of resin before pyrolysis fixed to graphite or primary exfoliated graphite. Can do. Further, in the heating during the above-described thermal decomposition, the C / O ratio can be increased by increasing the concentration of the inert gas and decreasing the oxygen concentration.
　本発明の炭素材料のＢＥＴ比表面積は、特に限定されないが、好ましくは１０ｍ２／ｇ以上、より好ましくは１５ｍ２／ｇ以上、好ましくは２００ｍ２／ｇ以下、より好ましくは１６０ｍ２／ｇ以下である。炭素材料のＢＥＴ比表面積が上記下限以上である場合、電解液の保液性をより一層高めることができ、蓄電デバイスの容量などの電池特性をより一層高めることができる。また、炭素材料のＢＥＴ比表面積が上記上限以下である場合、上記炭素材料を含むスラリーを集電体上に塗工して電極を形成する際の塗工性をより一層高めることができる。また、導電性をより一層高めることもできる。さらには、上記炭素材料と電解液との反応場が減少することから、電解液の劣化をより一層抑制することもできる。 The BET specific surface area of the carbon material of the present invention is not particularly limited, but is preferably 10 m 2 / g or more, more preferably 15 m 2 / g or more, preferably 200 m 2 / g or less, more preferably 160 m 2 / g or less. is there. When the BET specific surface area of a carbon material is more than the said minimum, the liquid retention property of electrolyte solution can be improved further and battery characteristics, such as the capacity | capacitance of an electrical storage device, can be improved further. Moreover, when the BET specific surface area of a carbon material is below the said upper limit, the coating property at the time of forming the electrode by coating the slurry containing the said carbon material on a collector can be improved further. In addition, the conductivity can be further increased. Furthermore, since the reaction field between the carbon material and the electrolytic solution is reduced, the deterioration of the electrolytic solution can be further suppressed.
　本発明の炭素材料のＢＥＴ比表面積は、ＢＥＴ法に準拠して、窒素の吸着等温線から測定することができる。測定装置としては、例えば、島津製作所社製、品番「ＡＳＡＰ－２０００」を用いることができる。 The BET specific surface area of the carbon material of the present invention can be measured from a nitrogen adsorption isotherm according to the BET method. As a measuring device, for example, product number “ASAP-2000” manufactured by Shimadzu Corporation can be used.
　［蓄電デバイス用電極］
　本発明の炭素材料は、蓄電デバイス用電極、すなわち、蓄電デバイスの正極及び／又は負極に用いることができる。なかでも、非水電解質二次電池、特にリチウムイオン二次電池の正極の導電助剤として用いた場合には、サイクル特性をより一層向上させることができるので、正極の導電助剤に好適に用いることができる。また、この場合、本発明の炭素材料を用いることにより、正極の導電性をより一層高めることができるので、正極中における導電助剤の含有量を少なくすることができる。そのため、正極活物質の含有量をより一層多くすることができ、蓄電デバイスのエネルギー密度をより一層大きくすることができる。 [Electrode for power storage devices]
The carbon material of the present invention can be used for an electrode for an electricity storage device, that is, a positive electrode and / or a negative electrode of the electricity storage device. In particular, when used as a conductive aid for a non-aqueous electrolyte secondary battery, particularly a positive electrode of a lithium ion secondary battery, the cycle characteristics can be further improved, so it is preferably used as a positive electrode conductive aid. be able to. In this case, the conductivity of the positive electrode can be further increased by using the carbon material of the present invention, so that the content of the conductive auxiliary agent in the positive electrode can be reduced. Therefore, the content of the positive electrode active material can be further increased, and the energy density of the electricity storage device can be further increased.
　上記正極は、一般的な正極構成、組成、及び製造方法のものでもよいし、正極活物質と本発明の炭素材料との複合体を用いてもよい。なお、蓄電デバイス用電極が負極である場合は、負極活物質として、例えば、天然黒鉛、人造黒鉛、ハードカーボン、金属酸化物、チタン酸リチウム、又はシリコン系の活物質を用いることができる。 The positive electrode may have a general positive electrode configuration, composition, and manufacturing method, or a composite of the positive electrode active material and the carbon material of the present invention. In the case where the electrode for the electricity storage device is a negative electrode, as the negative electrode active material, for example, natural graphite, artificial graphite, hard carbon, metal oxide, lithium titanate, or silicon-based active material can be used.
　蓄電デバイス用電極１００重量％中における上記炭素材料の含有量は、好ましくは０．１重量％以上、より好ましくは０．２重量％以上、さらに好ましくは０．４重量％以上、好ましくは１０重量％以下、より好ましくは８重量％以下、さらに好ましくは５重量％以下である。上記炭素材料の含有量が上記範囲内にある場合、活物質の含有量をより一層多くすることができ、蓄電デバイスのエネルギー密度をより一層大きくすることができる。 The content of the carbon material in 100% by weight of the electrode for an electricity storage device is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, further preferably 0.4% by weight or more, preferably 10% by weight. % Or less, more preferably 8% by weight or less, and still more preferably 5% by weight or less. When the content of the carbon material is within the above range, the content of the active material can be further increased, and the energy density of the electricity storage device can be further increased.
　本発明の蓄電デバイス用電極においては、本発明の炭素材料を第１の炭素材料（特に断りがない限り、単に炭素材料と称するものとする）としたときに、第１の炭素材料とは異なる第２の炭素材料をさらに含んでいてもよい。 In the electrode for an electricity storage device of the present invention, when the carbon material of the present invention is the first carbon material (unless otherwise specified, it is simply referred to as a carbon material), it is different from the first carbon material. A second carbon material may be further included.
　第２の炭素材料としては、特に限定されず、グラフェン、人造黒鉛、粒状黒鉛化合物、繊維状黒鉛化合物、カーボンブラック又は活性炭が例示される。 The second carbon material is not particularly limited, and graphene, artificial graphite, granular graphite compound, fibrous graphite compound, carbon black or activated carbon is exemplified.
　以下、本発明の蓄電デバイス用電極の一例としての二次電池用正極について説明する。なお、蓄電デバイス用電極が二次電池用負極の場合も同様のバインダー等を用いることができるものとする。 Hereinafter, a positive electrode for a secondary battery as an example of an electrode for an electricity storage device of the present invention will be described. In addition, the same binder etc. can be used also when the electrode for electrical storage devices is a negative electrode for secondary batteries.
　本発明の蓄電デバイス用電極に用いられる正極活物質は、負極活物質の電池反応電位よりも、貴であればよい。その際、電池反応は、１族若しくは２族のイオンが関与していればよい。そのようなイオンとしては、例えば、Ｈイオン、Ｌｉイオン、Ｎａイオン、Ｋイオン、Ｍｇイオン、Ｃａイオン、又はＡｌイオンが挙げられる。以下、Ｌｉイオンが電池反応に関与する系について詳細を例示する。 The positive electrode active material used for the electrode for the electricity storage device of the present invention may be nobler than the battery reaction potential of the negative electrode active material. In that case, the battery reaction should just involve group 1 or group 2 ions. Examples of such ions include H ions, Li ions, Na ions, K ions, Mg ions, Ca ions, and Al ions. Hereinafter, the details of the system in which Li ions are involved in the battery reaction will be described.
　この場合、上記正極活物質としては、例えば、リチウム金属酸化物、リチウム硫化物、又は硫黄が挙げられる。 In this case, examples of the positive electrode active material include lithium metal oxide, lithium sulfide, and sulfur.
　リチウム金属酸化物としては、スピネル構造、層状岩塩構造、若しくはオリビン構造を有するもの、又はこれらの混合物が挙げられる。 Examples of the lithium metal oxide include those having a spinel structure, a layered rock salt structure, an olivine structure, or a mixture thereof.
　スピネル構造を有するリチウム金属酸化物としては、マンガン酸リチウムなどが例示される。 Examples of the lithium metal oxide having a spinel structure include lithium manganate.
　層状岩塩構造を有するリチウム金属酸化物としては、コバルト酸リチウム、ニッケル酸リチウム、三元系などが例示される。 Examples of the lithium metal oxide having a layered rock salt structure include lithium cobaltate, lithium nickelate, and ternary system.
　オリビン構造を有するリチウム金属酸化物としては、リン酸鉄リチウム、リン酸マンガン鉄リチウム、リン酸マンガンリチウムなどが例示される。 Examples of the lithium metal oxide having an olivine structure include lithium iron phosphate, lithium manganese iron phosphate, and lithium manganese phosphate.
　上記正極活物質は、所謂ドープ元素が含まれてもよい。上記正極活物質は、単独で用いてもよいし、２種類以上を併用してもよい。 The positive electrode active material may contain a so-called doping element. The said positive electrode active material may be used independently and may use 2 or more types together.
　上記正極は、正極活物質と上記炭素材料のみで形成されてもよいが、正極をより一層容易に形成する観点から、バインダーが含まれていてもよい。 The positive electrode may be formed only of the positive electrode active material and the carbon material, but a binder may be included from the viewpoint of forming the positive electrode more easily.
　上記バインダーとしては、特に限定されないが、例えば、ポリフッ化ビニリデン（ＰＶｄＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、スチレン－ブタジエンゴム、ポリイミド、及びそれらの誘導体からなる群から選ばれる少なくとも１種の樹脂を用いることができる。 The binder is not particularly limited. For example, at least one resin selected from the group consisting of polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber, polyimide, and derivatives thereof is used. Can be used.
　上記バインダーは、二次電池用正極をより一層容易に作製する観点から、非水溶媒又は水に溶解又は分散されていることが好ましい。 The above binder is preferably dissolved or dispersed in a non-aqueous solvent or water from the viewpoint of more easily producing a positive electrode for a secondary battery.
　非水溶媒は、特に限定されないが、例えば、Ｎ－メチル－２－ピロリドン（ＮＭＰ）、ジメチルホルムアミド、ジメチルアセトアミド、メチルエチルケトン、酢酸メチル、酢酸エチル又はテトラヒドロフランなどを挙げることができる。これらに、分散剤や、増粘剤を加えてもよい。 The non-aqueous solvent is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, ethyl acetate, and tetrahydrofuran. You may add a dispersing agent and a thickener to these.
　上記二次電池用正極に含まれるバインダーの量は、正極活物質１００重量部に対して、好ましくは０．３重量部以上、３０重量部以下であり、より好ましくは０．５重量部以上、１５重量部以下である。バインダーの量が上記範囲内にある場合、正極活物質と炭素材料との接着性を維持することができ、集電体との接着性をより一層高めることができる。 The amount of the binder contained in the positive electrode for a secondary battery is preferably 0.3 parts by weight or more and 30 parts by weight or less, more preferably 0.5 parts by weight or more, with respect to 100 parts by weight of the positive electrode active material. 15 parts by weight or less. When the amount of the binder is within the above range, the adhesion between the positive electrode active material and the carbon material can be maintained, and the adhesion with the current collector can be further enhanced.
　上記二次電池用正極の作製方法としては、例えば、正極活物質、炭素材料、並びにバインダーの混合物を、集電体上に形成させることによって作製する方法が挙げられる。 Examples of the method for producing the positive electrode for a secondary battery include a method of producing a mixture of a positive electrode active material, a carbon material, and a binder on a current collector.
　上記二次電池用正極をより一層容易に作製する観点から、以下のようにして作製することが好ましい。まず、正極活物質、炭素材料にバインダー溶液又は分散液を加えて混合することによりスラリーを作製する。次に、作製したスラリーを集電体上に塗布し、最後に溶媒を除去することによって二次電池用正極を作製する。 From the viewpoint of more easily producing the positive electrode for a secondary battery, it is preferable to produce it as follows. First, a slurry is prepared by adding and mixing a binder solution or a dispersion liquid to a positive electrode active material and a carbon material. Next, the produced slurry is applied on a current collector, and finally the solvent is removed to produce a positive electrode for a secondary battery.
　上記スラリーの作製方法としては、既存の方法を用いることができる。例えば、ミキサー等を用いて混合する方法が挙げられる。混合に用いられるミキサーとしては、特に限定されないが、プラネタリミキサー、ディスパー、薄膜旋回型ミキサー、ジェットミキサー、又は自公回転型ミキサー等が挙げられる。 As the method for preparing the slurry, an existing method can be used. For example, the method of mixing using a mixer etc. is mentioned. Although it does not specifically limit as a mixer used for mixing, A planetary mixer, a disper, a thin film swirl-type mixer, a jet mixer, or a self-rotation type mixer etc. are mentioned.
　上記スラリーの固形分濃度は、塗工をより一層容易に行う観点から、３０重量％以上、９５重量％以下が好ましい。貯蔵安定性をより一層高める観点から、上記スラリーの固形分濃度は、３５重量％以上、９０重量％以下であることがより好ましい。また、より一層製造費用を抑制する観点から、上記スラリーの固形分濃度は、４０重量％以上、８５重量％以下であることがさらに好ましい。 The solid content concentration of the slurry is preferably 30% by weight or more and 95% by weight or less from the viewpoint of facilitating coating. From the viewpoint of further improving the storage stability, the solid content concentration of the slurry is more preferably 35% by weight or more and 90% by weight or less. Further, from the viewpoint of further reducing the production cost, the solid content concentration of the slurry is more preferably 40% by weight or more and 85% by weight or less.
　なお、上記固形分濃度は、希釈溶媒によって制御することができる。希釈溶媒としては、バインダー溶液、又は分散液と同じ種類の溶媒を用いることが好ましい。また、溶媒の相溶性があれば、他の溶媒を用いてもよい。 The solid content concentration can be controlled by a diluent solvent. As the diluting solvent, it is preferable to use the same type of solvent as the binder solution or dispersion. Further, other solvents may be used as long as the solvents are compatible.
　上記二次電池用正極に用いる集電体は、アルミニウム又はアルミニウムを含む合金であることが好ましい。アルミニウムは、正極反応雰囲気下で安定であることから、特に限定されないが、ＪＩＳ規格１０３０、１０５０、１０８５、１Ｎ９０、１Ｎ９９等に代表される高純度アルミニウムであることが好ましい。 The current collector used for the positive electrode for the secondary battery is preferably aluminum or an alloy containing aluminum. Aluminum is not particularly limited because it is stable in the positive electrode reaction atmosphere, but is preferably high-purity aluminum represented by JIS standards 1030, 1050, 1085, 1N90, 1N99, and the like.
　集電体の厚みは、特に限定されないが、１０μｍ以上、１００μｍ以下であることが好ましい。集電体の厚みが１０μｍ未満の場合、作製の観点から取り扱いが困難となることがある。一方、集電体の厚みが１００μｍより厚い場合は、経済的観点から不利になることがある。 The thickness of the current collector is not particularly limited, but is preferably 10 μm or more and 100 μm or less. When the thickness of the current collector is less than 10 μm, handling may be difficult from the viewpoint of production. On the other hand, when the thickness of the current collector is thicker than 100 μm, it may be disadvantageous from an economic viewpoint.
　なお、集電体は、アルミニウム以外の金属（銅、ＳＵＳ、ニッケル、チタン、及びそれらの合金）の表面に、アルミニウムを被覆させたものであってもよい。 The current collector may be one in which the surface of a metal other than aluminum (copper, SUS, nickel, titanium, and alloys thereof) is coated with aluminum.
　上記スラリーを集電体に塗布する方法としては、特に限定されないが、例えば、上記スラリーをドクターブレード、ダイコータ又はコンマコータ等により塗布した後に溶剤を除去する方法や、スプレーにより塗布した後に溶剤を除去する方法、又はスクリーン印刷によって塗布した後に溶媒を除去する方法等が挙げられる。 The method of applying the slurry to the current collector is not particularly limited. For example, the method of removing the solvent after applying the slurry with a doctor blade, die coater or comma coater, or removing the solvent after applying with a spray. The method or the method of removing a solvent after apply | coating by screen printing, etc. are mentioned.
　上記溶媒を除去する方法は、より一層簡便であることから、送風オーブンや真空オーブンを用いた乾燥が好ましい。溶媒を除去する雰囲気としては、空気雰囲気、不活性ガス雰囲気、又は真空状態などが挙げられる。また、溶媒を除去する温度は、特に限定されないが、６０℃以上、２５０℃以下であることが好ましい。溶媒を除去する温度が６０℃未満では、溶媒の除去に時間を要する場合がある。一方、溶媒を除去する温度が２５０℃より高いと、バインダーが劣化する場合がある。 Since the method for removing the solvent is more simple, drying using a blowing oven or a vacuum oven is preferable. Examples of the atmosphere for removing the solvent include an air atmosphere, an inert gas atmosphere, and a vacuum state. The temperature for removing the solvent is not particularly limited, but is preferably 60 ° C. or higher and 250 ° C. or lower. If the temperature at which the solvent is removed is less than 60 ° C., it may take time to remove the solvent. On the other hand, if the temperature for removing the solvent is higher than 250 ° C., the binder may deteriorate.
　上記二次電池用正極は、所望の厚み、密度まで圧縮させてもよい。圧縮は、特に限定されないが、例えば、ロールプレスや、油圧プレス等を用いて行うことができる。 The secondary battery positive electrode may be compressed to a desired thickness and density. Although compression is not specifically limited, For example, it can carry out using a roll press, a hydraulic press, etc.
　圧縮後における上記二次電池用正極の厚みは、特に限定されないが、１０μｍ以上、１０００μｍ以下であることが好ましい。厚みが１０μｍ未満では、所望の容量を得ることが難しい場合がある。一方、厚みが１０００μｍより厚い場合は、所望の出力密度を得ることが難しい場合がある。 The thickness of the positive electrode for secondary battery after compression is not particularly limited, but is preferably 10 μm or more and 1000 μm or less. If the thickness is less than 10 μm, it may be difficult to obtain a desired capacity. On the other hand, when the thickness is thicker than 1000 μm, it may be difficult to obtain a desired output density.
　上記二次電池用正極は、正極１ｃｍ２当たりの電気容量が、０．５ｍＡｈ以上、１０．０ｍＡｈ以下であることが好ましい。電気容量が０．５ｍＡｈ未満である場合は、所望する容量の電池の大きさが大きくなる場合がある。一方、電気容量が１０．０ｍＡｈより大きい場合は、所望の出力密度を得ることが難しくなる場合がある。なお、正極１ｃｍ２当たりの電気容量の算出は、二次電池用正極作製後、リチウム金属を対極とした半電池を作製し、充放電特性を測定することによって算出してもよい。 The positive electrode for secondary battery preferably has an electric capacity per 1 cm 2 of positive electrode of 0.5 mAh or more and 10.0 mAh or less. When the electric capacity is less than 0.5 mAh, the size of the battery having a desired capacity may increase. On the other hand, when the electric capacity is greater than 10.0 mAh, it may be difficult to obtain a desired output density. In addition, the calculation of the electric capacity per 1 cm 2 of the positive electrode may be performed by preparing a half battery using a lithium metal as a counter electrode after preparing the positive electrode for the secondary battery and measuring the charge / discharge characteristics.
　二次電池用正極の正極１ｃｍ２当たりの電気容量は、特に限定されないが、集電体単位面積あたりに形成させる正極の重量で制御することができる。例えば、前述のスラリー塗工時の塗工厚みで制御することができる。 The electric capacity per 1 cm 2 of the positive electrode of the secondary battery positive electrode is not particularly limited, but can be controlled by the weight of the positive electrode formed per current collector unit area. For example, it can control by the coating thickness at the time of the above-mentioned slurry coating.
　また、上記正極は、正極活物質と上記炭素材料との複合体を用いてもよい。正極活物質－炭素材料複合体は、例えば、次のような手順で作製される。 The positive electrode may be a composite of a positive electrode active material and the carbon material. The positive electrode active material-carbon material composite is produced, for example, by the following procedure.
　最初に、上記炭素材料を溶媒に分散させた炭素材料の分散液（以下、炭素材料の分散液１）を作製する。次に、上記分散液１とは別に、正極活物質を溶媒に分散させた正極活物質の分散液（以下、正極活物質の分散液２）を作製する。 First, a carbon material dispersion in which the above carbon material is dispersed in a solvent (hereinafter, carbon material dispersion 1) is prepared. Next, separately from the dispersion liquid 1, a positive electrode active material dispersion liquid (hereinafter, positive electrode active material dispersion liquid 2) in which a positive electrode active material is dispersed in a solvent is prepared.
　次に、炭素材料の分散液１と、正極活物質の分散液２とを混合する。最後に、上記炭素材料及び上記正極活物質が含まれる分散液の溶媒を除去することによって、蓄電デバイス用電極に用いられる正極活物質と炭素材料との複合体（活物質－炭素材料複合体）が作製される。 Next, the carbon material dispersion 1 and the positive electrode active material dispersion 2 are mixed. Finally, by removing the solvent of the dispersion liquid containing the carbon material and the positive electrode active material, a composite of the positive electrode active material and the carbon material used for the electrode for the electricity storage device (active material-carbon material composite) Is produced.
　また、上述の作製方法以外にも、混合の順序を変えてもよいし、上記分散液１，２のいずれかが分散液ではなく乾式であってもよいし、全て乾式の状態で混合する方法でもよい。また、炭素材料と正極活物質と溶媒との混合物を、ミキサーで混合する方法、すなわち、後述の正極のスラリーの作製と、複合体の作製とを兼ねていてもよい。 In addition to the above-described manufacturing method, the order of mixing may be changed, and either of the dispersions 1 and 2 may be dry instead of the dispersion, or a method of mixing all in a dry state. But you can. Moreover, you may serve as the method of mixing the mixture of a carbon material, a positive electrode active material, and a solvent with a mixer, ie, preparation of the below-mentioned positive electrode slurry, and preparation of a composite.
　正極活物質や炭素材料を分散させる溶媒は、水系、非水系、水系と非水系との混合溶媒、又は異なる非水系溶媒の混合溶媒のいずれでもよい。また、炭素材料を分散させる溶媒と、正極活物質を分散させる溶媒は同じでもよいし、異なっていてもよい。異なっている場合は、互いの溶媒に相溶性があることが好ましい。 The solvent in which the positive electrode active material and the carbon material are dispersed may be any of aqueous, non-aqueous, a mixed solvent of aqueous and non-aqueous, or a mixed solvent of different non-aqueous solvents. The solvent for dispersing the carbon material and the solvent for dispersing the positive electrode active material may be the same or different. If they are different, it is preferable that the solvents are compatible with each other.
　非水系溶媒としては、特に限定されないが、例えば分散のしやすさから、メタノール、エタノール、プロパノールに代表されるアルコール系、テトラヒドロフラン又はＮ－メチル－２－ピロリドンなどの非水系溶媒を用いることができる。また、分散性をより一層向上させるため、上記溶媒に、界面活性剤などの分散剤が含まれてもよい。 The non-aqueous solvent is not particularly limited. For example, a non-aqueous solvent such as methanol, ethanol, propanol represented by propanol, tetrahydrofuran, or N-methyl-2-pyrrolidone can be used for ease of dispersion. . In order to further improve dispersibility, the solvent may contain a dispersant such as a surfactant.
　分散方法は、特に限定されないが、超音波による分散、ミキサーによる分散、ジェットミルによる分散、又は攪拌子による分散が挙げられる。 The dispersion method is not particularly limited, and examples include dispersion by ultrasonic waves, dispersion by a mixer, dispersion by a jet mill, and dispersion by a stirrer.
　炭素材料の分散液の固形分濃度は、特に限定されないが、炭素材料の重量を１とした場合に、溶媒の重量が０．５以上、１０００以下であることが好ましい。取り扱い性をより一層高める観点から、炭素材料の重量を１とした場合に、溶媒の重量が１以上、７５０以下であることがより好ましい。また、分散性をより一層高める観点から、炭素材料の重量を１とした場合に、溶媒の重量が２以上、５００以下であることがさらに好ましい。 The solid content concentration of the carbon material dispersion is not particularly limited, but when the weight of the carbon material is 1, the weight of the solvent is preferably 0.5 or more and 1000 or less. From the viewpoint of further improving the handleability, when the weight of the carbon material is 1, the weight of the solvent is more preferably 1 or more and 750 or less. Further, from the viewpoint of further improving dispersibility, when the weight of the carbon material is 1, the weight of the solvent is more preferably 2 or more and 500 or less.
　溶媒の重量が上記下限未満の場合は、炭素材料を所望の分散状態まで分散させることができない場合がある。一方、溶媒の重量が上記上限より大きい場合は、製造費用が増大する場合がある。 If the weight of the solvent is less than the above lower limit, the carbon material may not be dispersed to a desired dispersion state. On the other hand, when the weight of the solvent is larger than the above upper limit, the production cost may increase.
　正極活物質の分散液の固形分濃度は、特に限定されないが、正極活物質の重量を１とした場合に、溶媒の重量が０．５以上、１００以下であることが好ましい。取り扱い性をより一層高める観点から、溶媒の重量は、１以上、７５以下であることがより好ましい。また、分散性をより一層高める観点から、溶媒の重量は、５以上、５０以下であることがさらに好ましい。なお、溶媒の重量が上記下限未満の場合は、正極活物質を所望の分散状態まで分散させることができない場合がある。一方、溶媒の重量が上記上限より大きい場合は、製造費用が増大する場合がある。 The solid content concentration of the positive electrode active material dispersion is not particularly limited, but when the weight of the positive electrode active material is 1, the weight of the solvent is preferably 0.5 or more and 100 or less. From the viewpoint of further improving the handleability, the weight of the solvent is more preferably 1 or more and 75 or less. Further, from the viewpoint of further improving dispersibility, the weight of the solvent is more preferably 5 or more and 50 or less. In addition, when the weight of the solvent is less than the lower limit, the positive electrode active material may not be dispersed to a desired dispersion state. On the other hand, when the weight of the solvent is larger than the above upper limit, the production cost may increase.
　正極活物質の分散液と、炭素材料の分散液とを混合する方法は、特に限定されないが、互いの分散液を一度に混合する方法や、一方の分散液を他方の分散液に複数回に分けて加える方法が挙げられる。 The method of mixing the dispersion of the positive electrode active material and the dispersion of the carbon material is not particularly limited, but a method of mixing each other's dispersion at once, or one dispersion into the other dispersion multiple times. A method of adding them separately is mentioned.
　一方の分散液を他方の分散液に複数回に分けて加える方法としては、例えば、スポイドなどの滴下の器具を用いて滴下する方法や、ポンプを用いる方法、又はディスペンサーを用いる方法が挙げられる。 Examples of the method of adding one dispersion to the other dispersion in a plurality of times include a method of dropping using a dropping device such as a spoid, a method of using a pump, or a method of using a dispenser.
　炭素材料、正極活物質及び溶媒の混合物から、溶媒を除去する方法としては、特に限定されないが、ろ過により溶媒を除去した後に、オーブン等で乾燥させる方法が挙げられる。上記ろ過は、生産性をより一層高める観点から、吸引ろ過であることが好ましい。また、乾燥方法としては、送風オーブンで乾燥させた後に、真空で乾燥させた場合、細孔に残存している溶媒を除去できることから好ましい。 The method for removing the solvent from the mixture of the carbon material, the positive electrode active material and the solvent is not particularly limited, and examples thereof include a method of removing the solvent by filtration and then drying it in an oven or the like. The filtration is preferably suction filtration from the viewpoint of further improving productivity. Moreover, as a drying method, when drying in a vacuum oven and then drying in a vacuum, it is preferable because the solvent remaining in the pores can be removed.
　活物質－炭素材料複合体における、正極活物質と炭素材料との重量の比率は、正極活物質の重量を１００重量％とした場合に、炭素材料の重量が、０．２重量％以上、１０．０重量％以下であることが好ましい。レート特性をより一層向上させる観点からは、炭素材料の重量が、０．３重量％以上、８．０重量％以下であることがより好ましい。また、サイクル特性をより一層向上させる観点からは、炭素材料の重量が、０．５重量％以上、７．０重量％以下であることがさらに好ましい。 The weight ratio of the positive electrode active material to the carbon material in the active material-carbon material composite is such that the weight of the carbon material is 0.2% by weight or more when the weight of the positive electrode active material is 100% by weight. It is preferable that it is 0.0 weight% or less. From the viewpoint of further improving the rate characteristics, the weight of the carbon material is more preferably 0.3% by weight or more and 8.0% by weight or less. Further, from the viewpoint of further improving the cycle characteristics, the weight of the carbon material is more preferably 0.5% by weight or more and 7.0% by weight or less.
　［蓄電デバイス］
　本発明の蓄電デバイスは、上記本発明の蓄電デバイス用電極を備える。そのため、炭素材料と電解液の反応性を小さくすることができ、蓄電デバイスのサイクル特性に代表される電池特性を高めることができる。 [Power storage device]
An electricity storage device of the present invention includes the electrode for an electricity storage device of the present invention. Therefore, the reactivity between the carbon material and the electrolytic solution can be reduced, and battery characteristics represented by the cycle characteristics of the electricity storage device can be improved.
　上述したように、本発明の蓄電デバイスとしては、特に限定されないが、非水電解質一次電池、水系電解質一次電池、非水電解質二次電池、水系電解質二次電池、全固体電解質一次電池、全固体電解質二次電池、コンデンサ、電気二重層キャパシタ、又はリチウムイオンキャパシタなどが例示される。 As described above, the electricity storage device of the present invention is not particularly limited, but non-aqueous electrolyte primary battery, aqueous electrolyte primary battery, non-aqueous electrolyte secondary battery, aqueous electrolyte secondary battery, all-solid electrolyte primary battery, all solid Examples include an electrolyte secondary battery, a capacitor, an electric double layer capacitor, and a lithium ion capacitor.
　本発明の蓄電デバイスの一例としての二次電池は、アルカリ金属イオン又はアルカリ土類金属イオンの挿入及び脱離反応が進行する化合物を用いられたものであればよい。アルカリ金属イオンとしては、リチウムイオン、ナトリウムイオン、又はカリウムイオンが例示される。アルカリ土類金属イオンとしては、カルシウムイオン又はマグネシウムイオンが例示される。特に、本発明は非水電解質二次電池の正極に効果が大きく、そのなかでもリチウムイオンを用いたものに好適に用いることができる。以下、リチウムイオンを用いた非水電解質二次電池（以下、リチウムイオン二次電池）を例に説明する。 The secondary battery as an example of the electricity storage device of the present invention may be any battery using a compound that undergoes insertion and desorption reactions of alkali metal ions or alkaline earth metal ions. Examples of alkali metal ions include lithium ions, sodium ions, and potassium ions. Examples of the alkaline earth metal ions include calcium ions and magnesium ions. In particular, the present invention is highly effective for the positive electrode of a non-aqueous electrolyte secondary battery, and among them, it can be suitably used for those using lithium ions. Hereinafter, a non-aqueous electrolyte secondary battery using lithium ions (hereinafter referred to as a lithium ion secondary battery) will be described as an example.
　上記非水電解質二次電池の正極及び負極は、集電体の両面に同じ電極を形成させた形態であってもよく、集電体の片面に正極、他方の面に負極を形成させた形態、すなわち、バイポーラ電極であってもよい。 The positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery may be in the form in which the same electrode is formed on both sides of the current collector, the form in which the positive electrode is formed on one side of the current collector and the negative electrode is formed on the other side That is, it may be a bipolar electrode.
　上記非水電解質二次電池は、正極側と負極側との間にセパレータを配置したものを倦回したものであってもよいし、積層したものであってもよい。正極、負極及びセパレータには、リチウムイオン伝導を担う非水電解質が含まれている。 The non-aqueous electrolyte secondary battery may be one obtained by winding or laminating a separator disposed between the positive electrode side and the negative electrode side. The positive electrode, the negative electrode, and the separator contain a non-aqueous electrolyte that is responsible for lithium ion conduction.
　上記非水電解質二次電池は、上記積層体を倦回、又は複数積層した後にラミネートフィルムで外装してもよいし、角形、楕円形、円筒形、コイン形、ボタン形、又はシート形の金属缶で外装してもよい。外装には発生したガスを放出するための機構が備わっていてもよい。積層体の積層数は、特に限定されず、所望の電圧値、電池容量を発現するまで積層させることができる。 The non-aqueous electrolyte secondary battery may be wound with a laminate film after the laminate is wound or laminated, or a metal having a square shape, an elliptical shape, a cylindrical shape, a coin shape, a button shape, or a sheet shape. It may be packaged with a can. The exterior may be provided with a mechanism for releasing the generated gas. The number of stacked layers is not particularly limited, and the stacked body can be stacked until a desired voltage value and battery capacity are developed.
　上記非水電解質二次電池は、所望の大きさ、容量、電圧によって、適宜直列、並列に接続した組電池とすることができる。上記組電池においては、各電池の充電状態の確認、安全性向上のため、組電池に制御回路が付属されていることが好ましい。 The non-aqueous electrolyte secondary battery can be an assembled battery connected in series or in parallel, depending on the desired size, capacity, and voltage. In the assembled battery, it is preferable that a control circuit is attached to the assembled battery in order to confirm the state of charge of each battery and improve safety.
　上記非水電解質二次電池に用いる非水電解質は、特に限定されないが、例えば、非水溶媒に溶質を溶解させた電解液を用いることができる。また、非水溶媒に溶質を溶解させた電解液を高分子に含浸させたゲル電解質、ポリエチレンオキシド、ポリプロピレンオキシドなどの高分子固体電解質、又はサルファイドガラス、オキシナイトライドなどの無機固体電解質を用いてもよい。 The non-aqueous electrolyte used for the non-aqueous electrolyte secondary battery is not particularly limited. For example, an electrolytic solution in which a solute is dissolved in a non-aqueous solvent can be used. In addition, a gel electrolyte obtained by impregnating a polymer with an electrolyte solution in which a solute is dissolved in a nonaqueous solvent, a solid polymer electrolyte such as polyethylene oxide or polypropylene oxide, or an inorganic solid electrolyte such as sulfide glass or oxynitride is used. Also good.
　非水溶媒としては、後述の溶質をより一層溶解させやすいことから、環状の非プロトン性溶媒及び／又は鎖状の非プロトン性溶媒を含むことが好ましい。 As the non-aqueous solvent, it is preferable to include a cyclic aprotic solvent and / or a chain aprotic solvent because solutes described later are more easily dissolved.
　環状の非プロトン性溶媒としては、環状カーボネート、環状エステル、環状スルホン又は環状エーテルなどが例示される。 Examples of the cyclic aprotic solvent include cyclic carbonates, cyclic esters, cyclic sulfones, and cyclic ethers.
　鎖状の非プロトン性溶媒としては、鎖状カーボネート、鎖状カルボン酸エステル又は鎖状エーテルなどが例示される。 Examples of the chain aprotic solvent include chain carbonate, chain carboxylic acid ester, chain ether and the like.
　また、アセトニトリルなどの一般的に非水電解質の溶媒として用いられる溶媒を用いてもよい。より具体的には、ジメチルカーボネート、メチルエチルカーボネート、ジメチルカーボネート、ジプロピルカーボネート、メチルプロピルカーボネート、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、γ－ブチルラクトン、１，２－ジメトキシエタン、スルホラン、ジオキソラン、プロピオン酸メチルなどを用いることができる。これら溶媒は単独で用いてもよいし、２種類以上の溶媒を混合しても用いてもよい。もっとも、後述の溶質をより一層容易に溶解させ、リチウムイオンの伝導性をより一層高める観点から、２種類以上の溶媒を混合した溶媒を用いることが好ましい。 Further, a solvent generally used as a solvent for nonaqueous electrolytes such as acetonitrile may be used. More specifically, dimethyl carbonate, methyl ethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyl lactone, 1,2-dimethoxyethane, sulfolane, dioxolane, propion For example, methyl acid can be used. These solvents may be used alone, or two or more kinds of solvents may be mixed and used. However, it is preferable to use a solvent in which two or more kinds of solvents are mixed from the viewpoint of further easily dissolving a solute described later and further improving the conductivity of lithium ions.
　溶質としては、特に限定されないが、ＬｉＣｌＯ４、ＬｉＢＦ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＢＯＢ（Ｌｉｔｈｉｕｍ　Ｂｉｓ　（Ｏｘａｌａｔｏ）　Ｂｏｒａｔｅ）、又はＬｉＮ（ＳＯ２ＣＦ３）２を用いることが好ましい。この場合、非水溶媒により一層容易に溶解させることができる。 The solute is not particularly limited, LiClO 4, LiBF 4, LiPF 6, LiAsF 6, LiCF 3 SO 3, LiBOB (Lithium Bis (Oxalato) Borate), or it is preferable to use a LiN (SO 2 CF 3) 2 . In this case, it can be dissolved more easily by a non-aqueous solvent.
　電解液に含まれる溶質の濃度は、０．５ｍｏｌ／Ｌ以上、２．０ｍｏｌ／Ｌ以下であることが好ましい。溶質の濃度が０．５ｍｏｌ／Ｌ未満では、所望のリチウムイオン伝導性が発現しない場合がある。一方、溶質の濃度が２．０ｍｏｌ／Ｌより高いと、溶質がそれ以上溶解しない場合がある。 The concentration of the solute contained in the electrolytic solution is preferably 0.5 mol / L or more and 2.0 mol / L or less. If the concentration of the solute is less than 0.5 mol / L, desired lithium ion conductivity may not be exhibited. On the other hand, if the concentration of the solute is higher than 2.0 mol / L, the solute may not dissolve further.
　また、非水電解質は、非水溶媒に溶質を溶解させた上述の電解液と、Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物とを含んでいることが好ましい。この場合、負極の表面に保護被膜を形成することができ、それによって負極内に充放電反応を阻害する物質が浸入することをより一層抑制することができる。従って、電解液と負極を構成する電極材料との反応をより一層抑制することができ、それによって非水電解質二次電池のサイクル特性に代表される電池特性の劣化をより一層抑制することができる。このように、Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物は、負極被膜形成用添加剤として用いることができる。 The nonaqueous electrolyte preferably contains the above-described electrolytic solution in which a solute is dissolved in a nonaqueous solvent and a compound that reacts with Li / Li + at 0.0 V or more and 2.0 V or less. . In this case, a protective film can be formed on the surface of the negative electrode, thereby further suppressing the intrusion of a substance that inhibits the charge / discharge reaction into the negative electrode. Therefore, the reaction between the electrolytic solution and the electrode material constituting the negative electrode can be further suppressed, and thereby the deterioration of the battery characteristics represented by the cycle characteristics of the nonaqueous electrolyte secondary battery can be further suppressed. . Thus, a compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + can be used as an additive for forming a negative electrode film.
　Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物の含有量は、非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下であることが好ましい。化合物の含有量が上記範囲にある場合、電解液と負極を構成する電極材料との反応による電池特性の劣化をさらに一層抑制することができる。 The content of the compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + is preferably 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte. . When content of a compound exists in the said range, deterioration of the battery characteristic by reaction with electrolyte solution and the electrode material which comprises a negative electrode can be suppressed further.
　Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物としては、特に限定されないが、例えば、ビニレンカーボネート、フッ化エチレンカーボネート、エチレンサルファイト、１，３－プロパンスルトン、又はビフェニルなどを用いることができる。 A compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + is not particularly limited. For example, vinylene carbonate, fluorinated ethylene carbonate, ethylene sulfite, 1,3-propane sultone, or Biphenyl and the like can be used.
　また、非水電解質は、非水溶媒に溶質を溶解させた電解液と、Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物とを含んでいることが好ましい。この場合、正極の表面に保護被膜を形成することができ、それによって正極内に充放電反応を阻害する物質が浸入することをより一層抑制することができる。従って、電解液と正極を構成する電極材料との反応をより一層抑制することができ、それによって非水電解質二次電池のサイクル特性に代表される電池特性の劣化をより一層抑制することができる。このように、Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物は、正極被膜形成用添加剤として用いることができる。 Moreover, it is preferable that the nonaqueous electrolyte contains the electrolyte solution which melt | dissolved the solute in the nonaqueous solvent, and the compound which reacts by 2.0V or more and 5.0V or less with respect to Li / Li + . In this case, a protective film can be formed on the surface of the positive electrode, thereby further suppressing the intrusion of a substance that inhibits the charge / discharge reaction into the positive electrode. Accordingly, it is possible to further suppress the reaction between the electrolytic solution and the electrode material constituting the positive electrode, thereby further suppressing the deterioration of the battery characteristics represented by the cycle characteristics of the nonaqueous electrolyte secondary battery. . Thus, a compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + can be used as an additive for forming a positive electrode film.
　Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物の含有量は、非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下であることが好ましい。化合物の含有量が上記範囲にある場合、電解液と正極を構成する電極材料との反応による電池特性の劣化をさらに一層抑制することができる。 The content of the compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + is preferably 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte. . When content of a compound exists in the said range, deterioration of the battery characteristic by reaction with electrolyte solution and the electrode material which comprises a positive electrode can be suppressed further.
　Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物としては、特に限定されないが、例えば、１，２－ジシアノエタンなどのジニトリル化合物、トリエチルホスホノアセテートに代表されるホスホン酸エステル、無水コハク酸や無水マレイン酸に代表される環状酸無水物などを用いることができる。 The compound that reacts at 2.0 V or more and 5.0 V or less with respect to Li / Li + is not particularly limited. For example, dinitrile compounds such as 1,2-dicyanoethane, phosphones represented by triethylphosphonoacetate, and the like. Acid esters, cyclic acid anhydrides represented by succinic anhydride and maleic anhydride, and the like can be used.
　なお、上記化合物は１種類のみで用いてもよいし、２種類以上混合して用いてもよい。 In addition, the said compound may be used only by 1 type, and may be used in mixture of 2 or more types.
　また、非水電解質には、難燃剤、安定化剤などの添加剤がさらに含まれていてもよい。 In addition, the nonaqueous electrolyte may further contain additives such as a flame retardant and a stabilizer.
　以下、実施例により本発明をさらに具体的に説明するが、本発明はこれらの実施例によって何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更可能である。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples and can be appropriately changed without departing from the scope of the present invention.
　（実施例１）
　次に、膨張化黒鉛の粉末（東洋炭素社製、商品名「ＰＦパウダー８Ｆ」、ＢＥＴ比表面積＝２２ｍ２／ｇ、平均粒子径＝１０μｍ）６ｇと、カルボキシメチルセルロースナトリウム塩０．２ｇと、水２００ｇとポリエチレングリコール１２ｇとを、ホモミクサーで３０分間混合することによって、原料組成物を作製した。 (Example 1)
Next, 6 g of expanded graphite powder (manufactured by Toyo Tanso Co., Ltd., trade name “PF powder 8F”, BET specific surface area = 22 m 2 / g, average particle size = 10 μm), 0.2 g of sodium carboxymethylcellulose, water A raw material composition was prepared by mixing 200 g and 12 g of polyethylene glycol with a homomixer for 30 minutes.
　なお、カルボキシメチルセルロースナトリウム塩は、アルドリッチ社製のもの（平均分子量＝２５０，０００）を用いた。ポリエチレングリコールは、三洋化成工業社製、商品名「ＰＧ６００」を用いた。また、ホモミクサーは、ＴＯＫＵＳＨＵ　ＫＩＫＡ社製、型番「Ｔ．Ｋ．ＨＯＭＯＭＩＸＥＲ　ＭＡＲＫＩＩ」を用いた。 In addition, the carboxymethylcellulose sodium salt manufactured by Aldrich (average molecular weight = 250,000) was used. As the polyethylene glycol, trade name “PG600” manufactured by Sanyo Chemical Industries, Ltd. was used. As the homomixer, model number “TKHOMOMIXER MARKII” manufactured by TOKUSHU KIKA Corporation was used.
　次に、作製した原料組成物を１５０℃で加熱処理することによって、水を除去した。その後、水を除去した組成物を、３７０℃の温度で、１時間加熱処理することよって、ポリエチレングリコールの一部が残存している炭素材料を作製した。 Next, the produced raw material composition was heat-treated at 150 ° C. to remove water. Thereafter, the composition from which water was removed was heat-treated at a temperature of 370 ° C. for 1 hour, thereby producing a carbon material in which a part of polyethylene glycol remained.
　最後に、作製した炭素材料を４２０℃で０．５時間加熱処理（以下、加熱処理Ａともいう）することによって、グラファイト構造を有し、部分的にグラファイトが剥離されている、炭素材料を得た。得られた炭素材料においては、全重量に対して３．０重量％樹脂が含まれていた。なお、樹脂量は、ＴＧ（日立ハイテクサイエンス社製、品番「ＳＴＡ７３００」）を用いて、２００℃～６００℃の範囲で重量減少した分を樹脂量として算出した。 Finally, the produced carbon material is heat-treated at 420 ° C. for 0.5 hours (hereinafter, also referred to as “heat treatment A”) to obtain a carbon material having a graphite structure and partially exfoliated graphite. It was. The obtained carbon material contained 3.0% by weight of resin with respect to the total weight. The amount of resin was calculated as the amount of resin using TG (manufactured by Hitachi High-Tech Science Co., Ltd., product number “STA7300”) in the range of 200 ° C. to 600 ° C.
　（実施例２）
　加熱処理Ａの加熱時間を３時間にしたこと以外は実施例１と同様にして炭素材料を得た。 (Example 2)
A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 3 hours.
　（実施例３）
　加熱処理Ａの加熱時間を２時間にしたこと以外は実施例１と同様にして炭素材料を得た。 Example 3
A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 2 hours.
　（実施例４）
　加熱処理Ａの加熱時間を１．５時間にしたこと以外は実施例１と同様にして炭素材料を得た。 (Example 4)
A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 1.5 hours.
　（実施例５）
　加熱処理Ａの加熱時間を２．５時間にしたこと以外は実施例１と同様にして炭素材料を得た。 (Example 5)
A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 2.5 hours.
　（実施例６）
　加熱処理Ａの加熱時間を１時間にしたこと以外は実施例１と同様にして炭素材料を得た。 (Example 6)
A carbon material was obtained in the same manner as in Example 1 except that the heating time of the heat treatment A was 1 hour.
　（比較例１）
　膨張化黒鉛の粉末（東洋炭素社製、商品名「ＰＦパウダー８Ｆ」、ＢＥＴ比表面積＝２２ｍ２／ｇ、平均粒子径＝１０μｍ）６ｇと、カルボキシメチルセルロースナトリウム塩０．２ｇと、水２００ｇとポリエチレングリコール１２０ｇとを、ホモミクサーで３０分間混合することによって、原料組成物を作製した。 (Comparative Example 1)
6 g of expanded graphite powder (trade name “PF powder 8F”, manufactured by Toyo Tanso Co., Ltd., BET specific surface area = 22 m 2 / g, average particle size = 10 μm), 0.2 g of sodium carboxymethylcellulose, 200 g of water and polyethylene A raw material composition was prepared by mixing 120 g of glycol with a homomixer for 30 minutes.
　なお、カルボキシメチルセルロースナトリウム塩は、アルドリッチ社製のもの（平均分子量＝２５０，０００）を用いた。ポリエチレングリコールは、三洋化成工業社製、商品名「ＰＧ６００」を用いた。また、ホモミクサーは、ＴＯＫＵＳＨＵ　ＫＩＫＡ社製、型番「Ｔ．Ｋ．ＨＯＭＯＭＩＸＥＲ　ＭＡＲＫＩＩ」を用いた。 In addition, the carboxymethylcellulose sodium salt manufactured by Aldrich (average molecular weight = 250,000) was used. As the polyethylene glycol, trade name “PG600” manufactured by Sanyo Chemical Industries, Ltd. was used. As the homomixer, model number “TKHOMOMIXER MARKII” manufactured by TOKUSHU KIKA Corporation was used.
　次に、作製した原料組成物を１５０℃で加熱処理することによって、水を除去した。その後、水を除去した組成物を、３７０℃の温度で、１時間加熱処理することよって、ポリエチレングリコールの一部が残存している炭素材料を作製した。 Next, the produced raw material composition was heat-treated at 150 ° C. to remove water. Thereafter, the composition from which water was removed was heat-treated at a temperature of 370 ° C. for 1 hour, thereby producing a carbon material in which a part of polyethylene glycol remained.
　最後に、作製した炭素材料を４２０℃で０．５時間の順に加熱処理することによって、グラファイト構造を有し、部分的にグラファイトが剥離されている、炭素材料を得た。比較例１で得られた炭素材料においては、全重量に対して３８．７重量％樹脂が含まれていた。 Finally, the produced carbon material was heat-treated at 420 ° C. in the order of 0.5 hours to obtain a carbon material having a graphite structure and partially exfoliated graphite. The carbon material obtained in Comparative Example 1 contained 38.7 wt% resin with respect to the total weight.
　（比較例２）
　比較例２では、炭素材料として市販のカーボンブラック（デンカ社製、商品名「デンカブラック」）をそのまま用いた。 (Comparative Example 2)
In Comparative Example 2, commercially available carbon black (manufactured by Denka Co., Ltd., trade name “Denka Black”) was used as it was as the carbon material.
　（比較例３）
　比較例３では、炭素材料として市販の高配向性熱分解グラファイト（ＨＯＰＧ）をそのまま用いた。 (Comparative Example 3)
In Comparative Example 3, commercially available highly oriented pyrolytic graphite (HOPG) was used as it was as the carbon material.
　（評価）
　実施例１～６及び比較例１～３の炭素材料を用いて以下の評価を行った。結果を下記の表１に示す。 (Evaluation)
The following evaluation was performed using the carbon materials of Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1 below.
　Ｘ線回折評価；
　実施例１～６及び比較例１～３の各炭素材料とシリコン粉末（Ｎａｎｏ　Ｐｏｗｄｅｒ、純度≧９８％、粒径≦１００ｎｍ、アルドリッチ社製）とを重量比１：１の割合でサンプル瓶中にて混合することにより、測定試料としての混合粉末を作製した。作製した混合粉末を無反射Ｓｉ試料台にいれ、Ｘ線回折装置（Ｓｍａｒｔ　Ｌａｂ、リガク社製）に設置した。その後に、Ｘ線源：ＣｕＫα（波長１．５４１Å）、測定範囲：３°～８０°、スキャンスピード：５°／分の条件で、広角Ｘ線回折法によりＸ線回折スペクトルを測定した。得られた測定結果から、２θ＝２８°以上、３０°未満の範囲における最も高いピークの高さｂを１として規格化し、そのときの２θ＝２４°以上、２８℃未満の範囲における最も高いピークの高さａを算出した。最後にａとｂとの比、すなわち、ａ／ｂを算出した。 X-ray diffraction evaluation;
The carbon materials of Examples 1 to 6 and Comparative Examples 1 to 3 and silicon powder (Nano Powder, purity ≧ 98%, particle size ≦ 100 nm, manufactured by Aldrich) in a weight ratio of 1: 1 in the sample bottle And mixed to prepare a mixed powder as a measurement sample. The prepared mixed powder was put on a non-reflective Si sample stage and installed in an X-ray diffractometer (Smart Lab, manufactured by Rigaku Corporation). Thereafter, an X-ray diffraction spectrum was measured by a wide-angle X-ray diffraction method under the conditions of X-ray source: CuKα (wavelength: 1.541 mm), measurement range: 3 ° to 80 °, and scan speed: 5 ° / min. From the obtained measurement results, the highest peak height b in the range of 2θ = 28 ° or more and less than 30 ° is normalized as 1, and the highest peak in the range of 2θ = 24 ° or more and less than 28 ° C. at that time The height a was calculated. Finally, the ratio of a and b, that is, a / b was calculated.
　Ｃ／Ｏ比；
　実施例１～６及び比較例１～３の各炭素材料を試料台にいれ、Ｘ線光電子分光法（ＸＰＳ）の測定装置（ＰＨＩ５０００　ＶｅｒｓａＰｒｏｂｅＩＩ）に設置した。つぎに、Ｘ線源：ＡｌＫα、光電子取出角：４５度、Ｘ線ビーム径２００μｍ（５０Ｗ、１５ｋＶ）の条件で、光電子スペクトルを測定した。Ｂｉｎｄｉｎｇ　Ｅｎｅｒｇｙ：２８０ｅＶ～２９２ｅＶに現れるＣ１ｓスペクトルのピーク面積を、Ｂｉｎｄｉｎｇ　Ｅｎｅｒｇｙ：５２５ｅＶ～５４０ｅＶに現れるＯ１ｓスペクトルのピーク面積で除することによって、炭素材料に含まれる酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）を算出した。 C / O ratio;
The carbon materials of Examples 1 to 6 and Comparative Examples 1 to 3 were placed on a sample stage and installed in a measuring device (PHI5000 VersaProbeII) for X-ray photoelectron spectroscopy (XPS). Next, a photoelectron spectrum was measured under the conditions of X-ray source: AlKα, photoelectron extraction angle: 45 degrees, and X-ray beam diameter of 200 μm (50 W, 15 kV). The ratio of the number of carbon atoms to the number of oxygen atoms contained in the carbon material is determined by dividing the peak area of the C1s spectrum appearing in the binding energy: 280 eV to 292 eV by the peak area of the O1s spectrum appearing in the binding energy: 525 eV to 540 eV (C / O ratio) was calculated.
　サイクリックボルタンメトリーの評価；
　サイクリックボルタンメトリーの評価は、三極式セル（ＨＳ３極セル、宝泉社製）を用いて測定した。 Evaluation of cyclic voltammetry;
Evaluation of cyclic voltammetry was performed using a triode cell (HS triode cell, manufactured by Hosen Co., Ltd.).
　作用極は、次の手順で作製した。最初に、実施例１～６及び比較例１～３の各炭素材料（４．０ｇ）と、結着剤としてポリテトラフルオロエチレンの粉末（以下、ＰＴＦＥ、６－Ｊ、三井デュポンフロロケミカル社製）とを、メノウ乳鉢にて５分間混合することによって、混合粉末を作製した。次に、上記混合粉末を、アルミ箔（厚み２０μｍ、片面つや、ＵＡＣＪ社製）で挟んだのち、ロールプレス機（ロールギャップ１００μｍ、テスター産業社製）でプレスし、シート状の混合物を得た。最後に、上記シート状の混合物を１０ｍｍφの大きさに裁断することによって、作用極を作製した。作用極の重量、及び厚みは、それぞれ１０ｍｇ、及び１００μｍであった。 The working electrode was prepared by the following procedure. First, each carbon material (4.0 g) of Examples 1 to 6 and Comparative Examples 1 to 3 and a powder of polytetrafluoroethylene as a binder (hereinafter PTFE, 6-J, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) ) Was mixed in an agate mortar for 5 minutes to prepare a mixed powder. Next, the mixed powder was sandwiched between aluminum foils (thickness 20 μm, single-sided gloss, manufactured by UACJ), and then pressed with a roll press machine (roll gap 100 μm, manufactured by Tester Sangyo Co., Ltd.) to obtain a sheet-like mixture. . Finally, the working electrode was produced by cutting the sheet-like mixture into a size of 10 mmφ. The weight and thickness of the working electrode were 10 mg and 100 μm, respectively.
　三極式セルは次の通りに作製した。 The tripolar cell was produced as follows.
　最初に、三極式セル（ＨＳ３極セル、宝泉社製）の作用極箇所に上記作用極を設置した。次に、セパレータ（ポリオレフィン系の微多孔膜、２５μｍ、２４ｍｍφ）を設置し、対極設置箇所に対極としてＬｉ金属（１６ｍｍφ）を設置した。さらに、参照極設置箇所に、参照極としてＬｉ金属（内径１６ｍｍφ、外径２５ｍｍφ）を設置した。 First, the working electrode was installed at the working electrode location of a three-electrode cell (HS three-pole cell, Hosen Co., Ltd.). Next, a separator (polyolefin-based microporous film, 25 μm, 24 mmφ) was installed, and Li metal (16 mmφ) was installed as a counter electrode at a counter electrode installation location. Further, Li metal (inner diameter: 16 mmφ, outer diameter: 25 mmφ) was installed as a reference electrode at the reference electrode installation location.
　最後に、電解液（エチレンカーボネート／ジメチルカーボネート＝１／２体積％、ＬｉＰＦ６　１ｍｏｌ／Ｌ）を１．０ｍＬ入れた後に、密封することによって、評価用セルの三極式セルを作製した。 Finally, 1.0 mL of an electrolytic solution (ethylene carbonate / dimethyl carbonate = 1/2 volume%, LiPF 6 1 mol / L) was added and then sealed to prepare a three-electrode cell for evaluation.
　サイクリックボルタンメトリーの測定は次の通りに実施した。 Cyclic voltammetry measurement was performed as follows.
　最初に、評価用セルを電気化学測定装置（バイオロジック社製）に接続し、３時間放置した。次に、自然電位を測定した後に、掃印速度（１ｍＶ／ｓ）、２．５Ｖ－４．５Ｖの掃引範囲で電位を掃引した。この掃引は、２５℃±５℃の室温で、１０回繰り返した。最後に、最初の貴な電位側への掃印時における４．２５Ｖの電流値を読み、電極に含まれる炭素材料の重量で除することによって、炭素材料と電解液との反応に起因する電流値を算出した。 First, the evaluation cell was connected to an electrochemical measurement device (Biologic) and left for 3 hours. Next, after measuring the natural potential, the potential was swept within a sweep rate (1 mV / s) and a sweep range of 2.5 V to 4.5 V. This sweep was repeated 10 times at room temperature of 25 ° C. ± 5 ° C. Finally, by reading the current value of 4.25 V at the time of the first sweep to the noble potential side and dividing by the weight of the carbon material contained in the electrode, the current resulting from the reaction between the carbon material and the electrolyte solution The value was calculated.
　電池特性の評価；
　電池特性は、以下のようにして非水電解質二次電池を作製して評価した。 Evaluation of battery characteristics;
The battery characteristics were evaluated by producing a nonaqueous electrolyte secondary battery as follows.
　（正極）
　まず、実施例１～６及び比較例１～３の各炭素材料０．１ｇに、エタノール５．０ｇを加え、５時間超音波洗浄機（ＡＳ　ＯＮＥ社製）で処理し、炭素材料の分散液を調製した。 (Positive electrode)
First, 5.0 g of ethanol was added to 0.1 g of each of the carbon materials of Examples 1 to 6 and Comparative Examples 1 to 3, and the mixture was treated with an ultrasonic cleaner (AS ONE) for 5 hours. Was prepared.
　次に、正極活物質としてのＬｉＣｏ１／３Ｎｉ１／３Ｍｎ１／３Ｏ２を、非特許文献（Ｊｏｕｒｎａｌ　ｏｆ　ＰｏｗｅｒＳｏｕｒｃｅｓ，Ｖｏｌ．１４６，ｐｐ．６３６－６３９（２００５））に記載されている方法で作製した。 Next, LiCo 1/3 Ni 1/3 Mn 1/3 O 2 as a positive electrode active material is described in non-patent literature (Journal of PowerSources, Vol. 146, pp. 636-639 (2005)). It was produced by the method.
　すなわち、まず、水酸化リチウムと、コバルト、ニッケル及びマンガンのｍｏｌ比が１：１：１の３元水酸化物とを混合し混合物を得た。次に、この混合物を空気雰囲気下において、１０００℃で加熱することによって正極活物質を作製した。 That is, first, lithium hydroxide was mixed with ternary hydroxide having a molar ratio of cobalt, nickel and manganese of 1: 1: 1 to obtain a mixture. Next, this mixture was heated at 1000 ° C. in an air atmosphere to prepare a positive electrode active material.
　次に、エタノール９ｇに得られた正極活物質（ＬｉＣｏ１／３Ｎｉ１／３Ｍｎ１／３Ｏ２）３ｇを加え、マグネチックスターラーにて６００ｒｐｍで１０分攪拌することによって、正極活物質の分散液を調製した。 Next, 3 g of the positive electrode active material (LiCo 1/3 Ni 1/3 Mn 1/3 O 2 ) obtained in 9 g of ethanol was added and stirred at 600 rpm for 10 minutes with a magnetic stirrer, thereby A dispersion was prepared.
　さらに、上記炭素材料の分散液に、上記正極活物質の分散液をスポイトで滴下した。なお、滴下時は、炭素材料の分散液は、超音波洗浄機（ＡＳ　ＯＮＥ社製）で処理し続けた。その後、分散液の混合液をマグネチックスターラーで３時間攪拌した。 Further, the dispersion of the positive electrode active material was dropped into the dispersion of the carbon material with a dropper. In addition, at the time of dripping, the dispersion liquid of the carbon material was continuously treated with an ultrasonic cleaning machine (manufactured by AS ONE). Thereafter, the mixed liquid of the dispersion was stirred with a magnetic stirrer for 3 hours.
　最後に、分散液の混合液を吸引ろ過した後に、１１０℃で１時間真空乾燥することによって、正極活物質と炭素材料との複合体（活物質－炭素材料複合体）を作製した。正極の作製に必要な量は、上記の工程を繰り返すことによって作製した。 Finally, the mixed liquid of the dispersion was subjected to suction filtration, and then vacuum-dried at 110 ° C. for 1 hour to prepare a composite of the positive electrode active material and the carbon material (active material-carbon material composite). The amount necessary for the production of the positive electrode was produced by repeating the above steps.
　次に、上記複合体９６重量部に、バインダー（ＰＶｄＦ、固形分濃度１２重量％、ＮＭＰ溶液）を固形分が４重量部となるように混合し、スラリーを作製した。次に、このスラリーをアルミニウム箔（２０μｍ）に塗工した後に、送風オーブンにて１２０℃で１時間加熱し、溶媒を除去した後、１２０℃で１２時間真空乾燥した。次に、同様にしてアルミニウム箔の裏面にもスラリーを塗工及び乾燥させた。 Next, 96 parts by weight of the composite was mixed with a binder (PVdF, solid content concentration of 12% by weight, NMP solution) so that the solid content was 4 parts by weight to prepare a slurry. Next, this slurry was applied to an aluminum foil (20 μm), then heated in a blast oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours. Next, the slurry was applied and dried on the back surface of the aluminum foil in the same manner.
　最後に、ロールプレス機にて、上記正極をプレスした。 Finally, the positive electrode was pressed with a roll press.
　正極の容量は、単位面積当たりの電極重量、及び正極活物質の理論容量（１５０ｍＡｈ／ｇ）から算出した。その結果、正極の容量（片面あたり）は、５ｍＡｈ／ｃｍ２であった。 The capacity of the positive electrode was calculated from the electrode weight per unit area and the theoretical capacity (150 mAh / g) of the positive electrode active material. As a result, the capacity of the positive electrode (per one surface) was 5 mAh / cm 2 .
　（負極）
　負極は、次の通りに作製した。 (Negative electrode)
The negative electrode was produced as follows.
　最初に負極活物質（人造黒鉛）１００重量部にバインダー（ＰＶｄＦ、固形分濃度１２重量％、ＮＭＰ溶液）を固形分が５重量部となるように混合し、スラリーを作製した。次に前記スラリーを銅箔（２０μｍ）に塗工した後に、送風オーブンにて１２０℃で１時間加熱し、溶媒を除去した後、１２０℃で１２時間真空乾燥した。次に、同様にして銅箔の裏面にもスラリーを塗工及び乾燥させた。 First, 100 parts by weight of the negative electrode active material (artificial graphite) was mixed with a binder (PVdF, solid content concentration: 12% by weight, NMP solution) so that the solid content was 5 parts by weight to prepare a slurry. Next, the slurry was applied to a copper foil (20 μm), heated in a blowing oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours. Next, the slurry was applied and dried on the back surface of the copper foil in the same manner.
　最後に、ロールプレス機にて、プレスし、負極を作製した。負極の容量は、単位面積当たりの電極重量、及び負極活物質の理論容量（３５０ｍＡｈ／ｇ）から算出した。その結果、負極の容量（片面あたり）は、６．０ｍＡｈ／ｃｍ２であった。 Finally, it was pressed with a roll press to produce a negative electrode. The capacity of the negative electrode was calculated from the weight of the electrode per unit area and the theoretical capacity (350 mAh / g) of the negative electrode active material. As a result, the capacity (per side) of the negative electrode was 6.0 mAh / cm 2 .
　（非水電解質二次電池の製造）
　最初に、作製した正極（電極部分：４０ｍｍ×５０ｍｍ）、負極（電極部分：４５ｍｍ×５５ｍｍ）及びセパレータ（ポリオレフィン系の微多孔膜、２５μｍ、５０ｍｍ×６０ｍｍ）を、負極／セパレータ／正極／セパレータ／負極の順に、正極の容量が２００ｍＡｈ（正極１枚、負極２枚）となるように積層した。次に、両端の正極及び負極にそれぞれアルミニウムタブ及びニッケルめっき銅タブを振動溶着させた後に、袋状のアルミラミネートシートに入れ、３方を熱溶着させ、電解液封入前の非水電解質二次電池を作製した。さらに、上記電解液封入前の非水電解質二次電池を６０℃で３時間真空乾燥した後に、非水電解質（エチレンカーボネート／ジメチルカーボネート＝１／２体積％、ＬｉＰＦ６　１ｍｏｌ／Ｌ）を２０ｇ入れ、減圧しながら封止することによって非水電解質二次電池を作製した。なお、ここまでの工程は、露点が－４０℃以下の雰囲気（ドライボックス）で実施した。最後に、非水電解質二次電池を、４．２５Ｖまで充電させた後に、２５℃で１００時間放置し、露点が－４０℃以下の雰囲気（ドライボックス）にて発生したガス、及び過剰な電解液を除去した後に、再度減圧しながら封止することによって非水電解質二次電池を作製した。 (Manufacture of non-aqueous electrolyte secondary batteries)
First, the produced positive electrode (electrode part: 40 mm × 50 mm), negative electrode (electrode part: 45 mm × 55 mm) and separator (polyolefin-based microporous membrane, 25 μm, 50 mm × 60 mm) were prepared as negative electrode / separator / positive electrode / separator / In order of the negative electrode, the layers were stacked so that the capacity of the positive electrode was 200 mAh (one positive electrode and two negative electrodes). Next, after vibration-welding aluminum tabs and nickel-plated copper tabs to the positive and negative electrodes at both ends, respectively, they are put into a bag-like aluminum laminate sheet and thermally welded on the three sides, and the non-aqueous electrolyte secondary before the electrolyte is sealed A battery was produced. Furthermore, after vacuum-drying the nonaqueous electrolyte secondary battery before enclosing the electrolyte solution at 60 ° C. for 3 hours, 20 g of nonaqueous electrolyte (ethylene carbonate / dimethyl carbonate = 1/2 vol%, LiPF 6 1 mol / L) was added. The nonaqueous electrolyte secondary battery was produced by sealing while reducing the pressure. The steps so far were performed in an atmosphere (dry box) having a dew point of −40 ° C. or lower. Finally, after charging the non-aqueous electrolyte secondary battery to 4.25 V, the battery is left at 25 ° C. for 100 hours, and the gas generated in an atmosphere (dry box) with a dew point of −40 ° C. or less and excessive electrolysis After removing the liquid, the nonaqueous electrolyte secondary battery was produced by sealing again while reducing the pressure.
　（サイクル特性）
　サイクル特性の評価は次の方法で行った。最初に、作製した非水電解質二次電池を４５℃の恒温槽に入れ、充放電装置（ＨＪ１００５ＳＤ８、北斗電工社製）に接続した。次に、定電流定電圧充電（電流値：２０ｍＡ、充電終止電圧：４．２５Ｖ、定電圧放電電圧：４．２５Ｖ、定電圧放電終止条件：３時間経過、又は電流値４ｍＡ）、定電流放電（電流値：１００ｍＡ、放電終止電圧：２．５Ｖ）を３００回繰り返すサイクル運転を行った。最後に、１回目の放電容量を１００としたときの、３００回目の放電容量の割合を算出することによって放電容量の維持率（サイクル特性）とした。なお、サイクル特性は、以下の評価基準で評価した。 (Cycle characteristics)
The cycle characteristics were evaluated by the following method. First, the produced nonaqueous electrolyte secondary battery was placed in a 45 ° C. thermostat and connected to a charge / discharge device (HJ1005SD8, manufactured by Hokuto Denko). Next, constant current constant voltage charge (current value: 20 mA, charge end voltage: 4.25 V, constant voltage discharge voltage: 4.25 V, constant voltage discharge end condition: 3 hours elapsed, or current value 4 mA), constant current discharge A cycle operation in which (current value: 100 mA, discharge end voltage: 2.5 V) was repeated 300 times was performed. Finally, the discharge capacity retention rate (cycle characteristics) was calculated by calculating the ratio of the 300th discharge capacity when the first discharge capacity was 100. The cycle characteristics were evaluated according to the following evaluation criteria.
　［評価基準］
　○…上記割合（サイクル特性）が８０％以上
　×…上記割合（サイクル特性）が８０％未満 [Evaluation criteria]
○: The above ratio (cycle characteristics) is 80% or more ×: The above ratio (cycle characteristics) is less than 80%
　結果を下記の表１に示す。 The results are shown in Table 1 below.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　（実施例７）
　実施例７では、以下のようにして非水電解質二次電池を作製して評価した。 (Example 7)
In Example 7, a nonaqueous electrolyte secondary battery was produced and evaluated as follows.
　（正極）
　まず、実施例１で得られた炭素材料０．１ｇに、エタノール５．０ｇを加え、５時間超音波洗浄機（ＡＳ　ＯＮＥ社製）で処理し、炭素材料の分散液を調製した。 (Positive electrode)
First, 5.0 g of ethanol was added to 0.1 g of the carbon material obtained in Example 1, and treated with an ultrasonic cleaner (manufactured by AS ONE) for 5 hours to prepare a carbon material dispersion.
　次に、正極活物質としてのＬｉＣｏ１／３Ｎｉ１／３Ｍｎ１／３Ｏ２を、非特許文献（Ｊｏｕｒｎａｌ　ｏｆ　ＰｏｗｅｒＳｏｕｒｃｅｓ，Ｖｏｌ．１４６，ｐｐ．６３６－６３９（２００５））に記載されている方法で作製した。 Next, LiCo 1/3 Ni 1/3 Mn 1/3 O 2 as a positive electrode active material is described in non-patent literature (Journal of PowerSources, Vol. 146, pp. 636-639 (2005)). It was produced by the method.
　すなわち、まず、水酸化リチウムと、コバルト、ニッケル及びマンガンのｍｏｌ比が１：１：１の３元水酸化物とを混合し混合物を得た。次に、この混合物を空気雰囲気下において、１０００℃で加熱することによって正極活物質を作製した。 That is, first, lithium hydroxide was mixed with ternary hydroxide having a molar ratio of cobalt, nickel and manganese of 1: 1: 1 to obtain a mixture. Next, this mixture was heated at 1000 ° C. in an air atmosphere to prepare a positive electrode active material.
　次に、エタノール９ｇに得られた正極活物質（ＬｉＣｏ１／３Ｎｉ１／３Ｍｎ１／３Ｏ２）３ｇを加え、マグネチックスターラーにて６００ｒｐｍで１０分攪拌することによって、正極活物質の分散液を調製した。 Next, 3 g of the positive electrode active material (LiCo 1/3 Ni 1/3 Mn 1/3 O 2 ) obtained in 9 g of ethanol was added and stirred at 600 rpm for 10 minutes with a magnetic stirrer, thereby A dispersion was prepared.
　さらに、上記炭素材料の分散液に、上記正極活物質の分散液をスポイトで滴下した。なお、滴下時は、炭素材料の分散液は、超音波洗浄機（ＡＳ　ＯＮＥ社製）で処理し続けた。その後、分散液の混合液をマグネチックスターラーで３時間攪拌した。 Further, the dispersion of the positive electrode active material was dropped into the dispersion of the carbon material with a dropper. In addition, at the time of dripping, the dispersion liquid of the carbon material was continuously treated with an ultrasonic cleaning machine (manufactured by AS ONE). Thereafter, the mixed liquid of the dispersion was stirred with a magnetic stirrer for 3 hours.
　最後に、分散液の混合液を吸引ろ過した後に、１１０℃で１時間真空乾燥することによって、正極活物質と炭素材料との複合体（活物質－炭素材料複合体）を作製した。正極の作製に必要な量は、上記の工程を繰り返すことによって作製した。 Finally, the mixed liquid of the dispersion was subjected to suction filtration, and then vacuum-dried at 110 ° C. for 1 hour to prepare a composite of the positive electrode active material and the carbon material (active material-carbon material composite). The amount necessary for the production of the positive electrode was produced by repeating the above steps.
　次に、上記複合体９６重量部に、バインダー（ＰＶｄＦ、固形分濃度１２重量％、ＮＭＰ溶液）を固形分が４重量部となるように混合し、スラリーを作製した。次に、このスラリーをアルミニウム箔（２０μｍ）に塗工した後に、送風オーブンにて１２０℃で１時間加熱し、溶媒を除去した後、１２０℃で１２時間真空乾燥した。次に、同様にしてアルミニウム箔の裏面にもスラリーを塗工及び乾燥させた。 Next, 96 parts by weight of the composite was mixed with a binder (PVdF, solid content concentration of 12% by weight, NMP solution) so that the solid content was 4 parts by weight to prepare a slurry. Next, this slurry was applied to an aluminum foil (20 μm), then heated in a blast oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours. Next, the slurry was applied and dried on the back surface of the aluminum foil in the same manner.
　最後に、ロールプレス機にて、上記正極をプレスした。 Finally, the positive electrode was pressed with a roll press.
　正極の容量は、単位面積当たりの電極重量、及び正極活物質の理論容量（１５０ｍＡｈ／ｇ）から算出した。その結果、正極の容量（片面あたり）は、５ｍＡｈ／ｃｍ２であった。 The capacity of the positive electrode was calculated from the electrode weight per unit area and the theoretical capacity (150 mAh / g) of the positive electrode active material. As a result, the capacity of the positive electrode (per one surface) was 5 mAh / cm 2 .
　（負極）
　負極は、次の通りに作製した。 (Negative electrode)
The negative electrode was produced as follows.
　最初に負極活物質（人造黒鉛）１００重量部にバインダー（ＰＶｄＦ、固形分濃度１２重量％、ＮＭＰ溶液）を固形分が５重量部となるように混合し、スラリーを作製した。次に前記スラリーを銅箔（２０μｍ）に塗工した後に、送風オーブンにて１２０℃で１時間加熱し、溶媒を除去した後、１２０℃で１２時間真空乾燥した。次に、同様にして銅箔の裏面にもスラリーを塗工及び乾燥させた。 First, 100 parts by weight of the negative electrode active material (artificial graphite) was mixed with a binder (PVdF, solid content concentration: 12% by weight, NMP solution) so that the solid content was 5 parts by weight to prepare a slurry. Next, the slurry was applied to a copper foil (20 μm), heated in a blowing oven at 120 ° C. for 1 hour to remove the solvent, and then vacuum-dried at 120 ° C. for 12 hours. Next, the slurry was applied and dried on the back surface of the copper foil in the same manner.
　最後に、ロールプレス機にて、プレスし、負極を作製した。負極の容量は、単位面積当たりの電極重量、及び負極活物質の理論容量（３５０ｍＡｈ／ｇ）から算出した。その結果、負極の容量（片面あたり）は、６．０ｍＡｈ／ｃｍ２であった。 Finally, it was pressed with a roll press to produce a negative electrode. The capacity of the negative electrode was calculated from the weight of the electrode per unit area and the theoretical capacity (350 mAh / g) of the negative electrode active material. As a result, the capacity (per side) of the negative electrode was 6.0 mAh / cm 2 .
　（非水電解質二次電池の製造）
　最初に、エチレンカーボネートとジメチルカーボネートとの体積比１：２における混合溶液に、ＬｉＰＦ６の濃度が１ｍｏｌ／Ｌとなるように溶解させ、電解液を作製した。次に、作製した電解液９９．５ｇと、ビニレンカーボネート（キシダ化学社製）０．５ｇとを混合して濃度が０．５重量％の非水電解質を調製した。 (Manufacture of non-aqueous electrolyte secondary batteries)
First, it was dissolved in a mixed solution of ethylene carbonate and dimethyl carbonate in a volume ratio of 1: 2 so that the concentration of LiPF 6 was 1 mol / L to prepare an electrolytic solution. Next, 99.5 g of the produced electrolyte solution and 0.5 g of vinylene carbonate (manufactured by Kishida Chemical Co., Ltd.) were mixed to prepare a non-aqueous electrolyte having a concentration of 0.5% by weight.
　次に、上記のようにして作製した正極（電極部分：４０ｍｍ×５０ｍｍ）、負極（電極部分：４５ｍｍ×５５ｍｍ）及びセパレータ（ポリオレフィン系の微多孔膜、２５μｍ、５０ｍｍ×６０ｍｍ）を、負極／セパレータ／正極／セパレータ／負極の順に、正極の容量が２００ｍＡｈ（正極１枚、負極２枚）となるように積層した。次に、両端の正極及び負極にそれぞれアルミニウムタブ及びニッケルめっき銅タブを振動溶着させた後に、袋状のアルミラミネートシートに入れ、３方を熱溶着させ、電解液封入前の非水電解質二次電池を作製した。さらに、上記電解液封入前の非水電解質二次電池を６０℃で３時間真空乾燥した後に、上記の方法で調製した非水電解質を１．０ｍＬ入れ、減圧しながら封止することによって非水電解質二次電池を作製した。 Next, the positive electrode (electrode portion: 40 mm × 50 mm), negative electrode (electrode portion: 45 mm × 55 mm) and separator (polyolefin-based microporous membrane, 25 μm, 50 mm × 60 mm) prepared as described above were used as the negative electrode / separator. The layers were laminated in the order of / positive electrode / separator / negative electrode so that the capacity of the positive electrode was 200 mAh (one positive electrode and two negative electrodes). Next, after vibration-welding aluminum tabs and nickel-plated copper tabs to the positive and negative electrodes at both ends, respectively, they are put into a bag-like aluminum laminate sheet and thermally welded on the three sides, and the non-aqueous electrolyte secondary before the electrolyte is sealed A battery was produced. Furthermore, after vacuum-drying the non-aqueous electrolyte secondary battery before encapsulating the electrolyte solution at 60 ° C. for 3 hours, 1.0 mL of the non-aqueous electrolyte prepared by the above method is added and sealed while reducing the pressure. An electrolyte secondary battery was produced.
　なお、ここまでの工程は、露点が－４０℃以下の雰囲気（ドライボックス）で実施した。最後に、非水電解質二次電池を、４．２５Ｖまで充電させた後に、２５℃で１００時間放置し、露点が－４０℃以下の雰囲気（ドライボックス）にて発生したガス、及び過剰な電解液を除去した後に、再度減圧しながら封止することによって非水電解質二次電池を作製した。 The steps so far were performed in an atmosphere (dry box) with a dew point of −40 ° C. or lower. Finally, after charging the non-aqueous electrolyte secondary battery to 4.25 V, the battery is left at 25 ° C. for 100 hours, and the gas generated in an atmosphere (dry box) with a dew point of −40 ° C. or less and excessive electrolysis After removing the liquid, the nonaqueous electrolyte secondary battery was produced by sealing again while reducing the pressure.
　（実施例８）
　非水電解質として、以下のようにして調製した非水電解質を用いたこと以外は実施例７と同様にして非水電解質二次電池を作製した。 (Example 8)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 7 except that the nonaqueous electrolyte prepared as follows was used as the nonaqueous electrolyte.
　最初に、エチレンカーボネートとジメチルカーボネートとの体積比１：２における混合溶液に、ＬｉＰＦ６の濃度が１ｍｏｌ／Ｌとなるように溶解させ、電解液を作製した。次に、作製した電解液９９ｇと、環状酸無水物として無水コハク酸（和光純薬工業社製）１ｇとを混合して濃度が１重量％の非水電解質を調製した。 First, it was dissolved in a mixed solution of ethylene carbonate and dimethyl carbonate in a volume ratio of 1: 2 so that the concentration of LiPF 6 was 1 mol / L to prepare an electrolytic solution. Next, 99 g of the prepared electrolytic solution and 1 g of succinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) as a cyclic acid anhydride were mixed to prepare a nonaqueous electrolyte having a concentration of 1% by weight.
　（サイクル特性）
　実施例７及び実施例８で作製した非水電解質二次電池のサイクル特性の評価は次の方法で行った。最初に、作製した非水電解質二次電池を４５℃の恒温槽に入れ、充放電装置（ＨＪ１００５ＳＤ８、北斗電工社製）に接続した。次に、定電流定電圧充電（電流値：２０ｍＡ、充電終止電圧：４．２５Ｖ、定電圧放電電圧：４．２５Ｖ、定電圧放電終止条件：３時間経過、又は電流値４ｍＡ）、定電流放電（電流値：１００ｍＡ、放電終止電圧：２．５Ｖ）を３００回繰り返すサイクル運転を行った。最後に、１回目の放電容量を１００としたときの、３００回目の放電容量の割合を算出することによって放電容量の維持率（サイクル特性）とした。なお、サイクル特性は、以下の評価基準で評価した。 (Cycle characteristics)
The cycle characteristics of the nonaqueous electrolyte secondary batteries produced in Example 7 and Example 8 were evaluated by the following method. First, the produced nonaqueous electrolyte secondary battery was placed in a 45 ° C. thermostat and connected to a charge / discharge device (HJ1005SD8, manufactured by Hokuto Denko). Next, constant current constant voltage charge (current value: 20 mA, charge end voltage: 4.25 V, constant voltage discharge voltage: 4.25 V, constant voltage discharge end condition: 3 hours elapsed, or current value 4 mA), constant current discharge A cycle operation in which (current value: 100 mA, discharge end voltage: 2.5 V) was repeated 300 times was performed. Finally, the discharge capacity retention rate (cycle characteristics) was calculated by calculating the ratio of the 300th discharge capacity when the first discharge capacity was 100. The cycle characteristics were evaluated according to the following evaluation criteria.
　［評価基準］
　○…上記割合（サイクル特性）が８０％以上
　×…上記割合（サイクル特性）が８０％未満 [Evaluation criteria]
○: The above ratio (cycle characteristics) is 80% or more ×: The above ratio (cycle characteristics) is less than 80%
　結果を下記の表２に示す。 The results are shown in Table 2 below.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002

Claims (9)

  1. 　グラフェン積層構造を有する炭素材料であって、
    　前記炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さａと、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さｂとの比ａ／ｂが、０．２以上、１０．０以下であり、
    　前記炭素材料が含まれる電極を作用電極とし、リチウム金属を参照電極及び対極とし、１ｍｏｌ／Ｌ濃度のＬｉＰＦ６と、エチレンカーボネートとジメチルカーボネートとの体積比１：２における混合溶液とを含む電解液を用いて、サイクリックボルタンメトリーにより測定した４．２５Ｖ（ｖｓ．Ｌｉ＋／Ｌｉ）の電位における電流値の絶対値が、０．００１Ａ／ｇ以上、０．０２Ａ／ｇ以下である、炭素材料。     A carbon material having a graphene laminated structure,
    When the X-ray diffraction spectrum of the mixture of the carbon material and Si at a weight ratio of 1: 1 was measured, the highest peak height a in the range where 2θ was 24 ° or more and less than 28 °, and 2θ was The ratio a / b of the highest peak height b in the range of 28 ° or more and less than 30 ° is 0.2 or more and 10.0 or less,
    Electrolyte containing the carbon material-containing electrode as a working electrode, lithium metal as a reference electrode and a counter electrode, and 1 mol / L concentration of LiPF 6 and a mixed solution of ethylene carbonate and dimethyl carbonate in a volume ratio of 1: 2. The carbon material whose absolute value of the electric current value in the electric potential of 4.25V (vs.Li <+ > / Li) measured by cyclic voltammetry is 0.001 A / g or more and 0.02 A / g or less.
  2. 　グラフェン積層構造を有する炭素材料であって、
    　前記炭素材料とＳｉとの重量比１：１における混合物のＸ線回折スペクトルを測定したときに、２θが、２４°以上、２８°未満の範囲における最も高いピークの高さａと、２θが、２８°以上、３０°未満の範囲における最も高いピークの高さｂとの比ａ／ｂが、０．２以上、１０．０以下であり、
    　前記炭素材料の元素分析により測定された酸素原子数に対する炭素原子数の比（Ｃ／Ｏ比）が、２０以上、２００以下である、炭素材料。     A carbon material having a graphene laminated structure,
    When the X-ray diffraction spectrum of the mixture of the carbon material and Si at a weight ratio of 1: 1 was measured, the highest peak height a in the range where 2θ was 24 ° or more and less than 28 °, and 2θ was The ratio a / b of the highest peak height b in the range of 28 ° or more and less than 30 ° is 0.2 or more and 10.0 or less,
    The carbon material whose ratio (C / O ratio) of the number of carbon atoms with respect to the number of oxygen atoms measured by the elemental analysis of the said carbon material is 20-200.
  3. 　前記炭素材料が、薄片化黒鉛である、請求項１又は２に記載の炭素材料。 The carbon material according to claim 1 or 2, wherein the carbon material is exfoliated graphite.
  4. 　前記炭素材料が、蓄電デバイス用電極に用いられる、請求項１～３のいずれか１項に記載の炭素材料。 The carbon material according to any one of claims 1 to 3, wherein the carbon material is used for an electrode for an electricity storage device.
  5. 　請求項１～４のいずれか１項に記載の炭素材料を含む、蓄電デバイス用電極。 An electrode for an electricity storage device comprising the carbon material according to any one of claims 1 to 4.
  6. 　請求項５に記載の蓄電デバイス用電極を備える、蓄電デバイス。 An electricity storage device comprising the electrode for an electricity storage device according to claim 5.
  7. 　請求項５に記載の蓄電デバイス用電極と、非水電解質とを備える、非水電解質二次電池。 A nonaqueous electrolyte secondary battery comprising the electricity storage device electrode according to claim 5 and a nonaqueous electrolyte.
  8. 　前記非水電解質が、非水溶媒に溶質を溶解させた電解液と、Ｌｉ／Ｌｉ＋に対して０．０Ｖ以上、２．０Ｖ以下で反応する化合物とを含み、前記化合物の含有量が、前記非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下である、請求項７に記載の非水電解質二次電池。 The non-aqueous electrolyte includes an electrolytic solution in which a solute is dissolved in a non-aqueous solvent, and a compound that reacts at 0.0 V or more and 2.0 V or less with respect to Li / Li + , and the content of the compound is The nonaqueous electrolyte secondary battery according to claim 7, which is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte.
  9. 　前記非水電解質が、非水溶媒に溶質を溶解させた電解液と、Ｌｉ／Ｌｉ＋に対して２．０Ｖ以上、５．０Ｖ以下で反応する化合物とを含み、前記化合物の含有量が、前記非水電解質１００重量％に対して０．０１重量％以上、１０重量％以下である、請求項７に記載の非水電解質二次電池。 The non-aqueous electrolyte includes an electrolytic solution in which a solute is dissolved in a non-aqueous solvent, and a compound that reacts at 2.0 V or higher and 5.0 V or lower with respect to Li / Li + , and the content of the compound is The nonaqueous electrolyte secondary battery according to claim 7, which is 0.01 wt% or more and 10 wt% or less with respect to 100 wt% of the nonaqueous electrolyte.
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